--- a/accessible/generic/Accessible.cpp
+++ b/accessible/generic/Accessible.cpp
@@ -857,20 +857,20 @@ Accessible::HandleAccEvent(AccEvent* aEv
           break;
         case nsIAccessibleEvent::EVENT_STATE_CHANGE: {
                                                        AccStateChangeEvent* event = downcast_accEvent(aEvent);
                                                        ipcDoc->SendStateChangeEvent(id, event->GetState(),
                                                                                     event->IsStateEnabled());
                                                        break;
                                                      }
         case nsIAccessibleEvent::EVENT_TEXT_CARET_MOVED: {
-                                                           AccCaretMoveEvent* event = downcast_accEvent(aEvent);
-                                                           ipcDoc->SendEvent(id, event->GetCaretOffset());
-                                                           break;
-                                                         }
+          AccCaretMoveEvent* event = downcast_accEvent(aEvent);
+          ipcDoc->SendCaretMoveEvent(id, event->GetCaretOffset());
+          break;
+        }
         case nsIAccessibleEvent::EVENT_TEXT_INSERTED:
         case nsIAccessibleEvent::EVENT_TEXT_REMOVED: {
           AccTextChangeEvent* event = downcast_accEvent(aEvent);
           ipcDoc->SendTextChangeEvent(id, event->ModifiedText(),
                                       event->GetStartOffset(),
                                       event->GetLength(),
                                       event->IsTextInserted(),
                                       event->IsFromUserInput());

--- a/b2g/branding/official/Makefile.in
+++ b/b2g/branding/official/Makefile.in
@@ -8,16 +8,19 @@ ifeq ($(MOZ_WIDGET_TOOLKIT),windows)
 BRANDING_FILES := \
 	app.ico \
 	$(NULL)
 endif
 
 ifeq ($(MOZ_WIDGET_TOOLKIT),cocoa)
 BRANDING_FILES := \
 	app.icns \
+	background.png \
+	disk.icns \
+	dsstore \
 	$(NULL)
 endif
 
 ifdef MOZ_WIDGET_GTK
 BRANDING_FILES := \
 	default.png \
 	$(NULL)
 endif

copy from browser/branding/nightly/background.png
copy to b2g/branding/official/background.png

copy from browser/branding/nightly/disk.icns
copy to b2g/branding/official/disk.icns

copy from browser/branding/nightly/dsstore
copy to b2g/branding/official/dsstore

--- a/b2g/branding/unofficial/Makefile.in
+++ b/b2g/branding/unofficial/Makefile.in
@@ -8,16 +8,19 @@ ifeq ($(MOZ_WIDGET_TOOLKIT),windows)
 BRANDING_FILES := \
 	app.ico \
 	$(NULL)
 endif
 
 ifeq ($(MOZ_WIDGET_TOOLKIT),cocoa)
 BRANDING_FILES := \
 	app.icns \
+	background.png \
+	disk.icns \
+	dsstore \
 	$(NULL)
 endif
 
 ifdef MOZ_WIDGET_GTK
 BRANDING_FILES := \
 	default.png \
 	$(NULL)
 endif

copy from browser/branding/nightly/background.png
copy to b2g/branding/unofficial/background.png

copy from browser/branding/nightly/disk.icns
copy to b2g/branding/unofficial/disk.icns

copy from browser/branding/nightly/dsstore
copy to b2g/branding/unofficial/dsstore

deleted file mode 100755
--- a/build/package/mac_osx/pkg-dmg
+++ /dev/null
@@ -1,1488 +0,0 @@
-#!/usr/bin/perl
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-use strict;
-use warnings;
-
-=pod
-
-=head1 NAME
-
-B<pkg-dmg> - Mac OS X disk image (.dmg) packager
-
-=head1 SYNOPSIS
-
-B<pkg-dmg>
-B<--source> I<source-folder>
-B<--target> I<target-image>
-[B<--format> I<format>]
-[B<--volname> I<volume-name>]
-[B<--tempdir> I<temp-dir>]
-[B<--mkdir> I<directory>]
-[B<--copy> I<source>[:I<dest>]]
-[B<--symlink> I<source>[:I<dest>]]
-[B<--license> I<file>]
-[B<--resource> I<file>]
-[B<--icon> I<icns-file>]
-[B<--attribute> I<a>:I<file>[:I<file>...]
-[B<--idme>]
-[B<--sourcefile>]
-[B<--verbosity> I<level>]
-[B<--dry-run>]
-
-=head1 DESCRIPTION
-
-I<pkg-dmg> takes a directory identified by I<source-folder> and transforms
-it into a disk image stored as I<target-image>.  The disk image will
-occupy the least space possible for its format, or the least space that the
-authors have been able to figure out how to achieve.
-
-=head1 OPTIONS
-
-=over 5
-
-==item B<--source> I<source-folder>
-
-Identifies the directory that will be packaged up.  This directory is not
-touched, a copy will be made in a temporary directory for staging purposes.
-See B<--tempdir>.
-
-==item B<--target> I<target-image>
-
-The disk image to create.  If it exists and is not in use, it will be
-overwritten.  If I<target-image> already contains a suitable extension,
-it will be used unmodified.  If no extension is present, or the extension
-is incorrect for the selected format, the proper extension will be added.
-See B<--format>.
-
-==item B<--format> I<format>
-
-The format to create the disk image in.  Valid values for I<format> are:
-     - UDZO - zlib-compressed, read-only; extension I<.dmg>
-     - UDBZ - bzip2-compressed, read-only; extension I<.dmg>;
-              create and use on 10.4 ("Tiger") and later only
-     - UDRW - read-write; extension I<.dmg>
-     - UDSP - read-write, sparse; extension I<.sparseimage>
-
-UDBZ is the default format.
-
-See L<hdiutil(1)> for a description of these formats.
-
-=item B<--volname> I<volume-name>
-
-The name of the volume in the disk image.  If not specified, I<volume-name>
-defaults to the name of the source directory from B<--source>.
-
-=item B<--tempdir> I<temp-dir>
-
-A temporary directory to stage intermediate files in.  I<temp-dir> must
-have enough space available to accommodate twice the size of the files
-being packaged.  If not specified, defaults to the same directory that
-the I<target-image> is to be placed in.  B<pkg-dmg> will remove any
-temporary files it places in I<temp-dir>.
-
-=item B<--mkdir> I<directory>
-
-Specifies a directory that should be created in the disk image.
-I<directory> and any ancestor directories will be created.  This is
-useful in conjunction with B<--copy>, when copying files to directories
-that may not exist in I<source-folder>.  B<--mkdir> may appear multiple
-times.
-
-=item B<--copy> I<source>[:I<dest>]
-
-Additional files to copy into the disk image.  If I<dest> is
-specified, I<source> is copied to the location I<dest> identifies,
-otherwise, I<source> is copied to the root of the new volume.  B<--copy>
-provides a way to package up a I<source-folder> by adding files to it
-without modifying the original I<source-folder>.  B<--copy> may appear
-multiple times.
-
-This option is useful for adding .DS_Store files and window backgrounds
-to disk images.
-
-=item B<--symlink> I<source>[:I<dest>]
-
-Like B<--copy>, but allows symlinks to point out of the volume. Empty symlink
-destinations are interpreted as "like the source path, but inside the dmg"
-
-This option is useful for adding symlinks to external resources,
-e.g. to /Applications.
-
-=item B<--license> I<file>
-
-A plain text file containing a license agreement to be displayed before
-the disk image is mounted.  English is the only supported language.  To
-include license agreements in other languages, in multiple languages,
-or to use formatted text, prepare a resource and use L<--resource>.
-
-=item B<--resource> I<file>
-
-A resource file to merge into I<target-image>.  If I<format> is UDZO or
-UDBZ, the disk image will be flattened to a single-fork file that contains
-the resource but may be freely transferred without any special encodings.
-I<file> must be in a format suitable for L<Rez(1)>.  See L<Rez(1)> for a
-description of the format, and L<hdiutil(1)> for a discussion on flattened
-disk images.  B<--resource> may appear multiple times.
-
-This option is useful for adding license agreements and other messages
-to disk images.
-
-=item B<--icon> I<icns-file>
-
-Specifies an I<icns> file that will be used as the icon for the root of
-the volume.  This file will be copied to the new volume and the custom
-icon attribute will be set on the root folder.
-
-=item B<--attribute> I<a>:I<file>[:I<file>...]
-
-Sets the attributes of I<file> to the attribute list in I<a>.  See
-L<SetFile(1)>
-
-=item B<--idme>
-
-Enable IDME to make the disk image "Internet-enabled."  The first time
-the image is mounted, if IDME processing is enabled on the system, the
-contents of the image will be copied out of the image and the image will
-be placed in the trash with IDME disabled.
-
-=item B<--sourcefile>
-
-If this option is present, I<source-folder> is treated as a file, and is
-placed as a file within the volume's root folder.  Without this option,
-I<source-folder> is treated as the volume root itself.
-
-=item B<--verbosity> I<level>
-
-Adjusts the level of loudness of B<pkg-dmg>.  The possible values for
-I<level> are:
-     0 - Only error messages are displayed.
-     1 - Print error messages and command invocations.
-     2 - Print everything, including command output.
-
-The default I<level> is 2.
-
-=item B<--dry-run>
-
-When specified, the commands that would be executed are printed, without
-actually executing them.  When commands depend on the output of previous
-commands, dummy values are displayed.
-
-=back
-
-=head1 NON-OPTIONS
-
-=over 5
-
-=item
-
-Resource forks aren't copied.
-
-=item
-
-The root folder of the created volume is designated as the folder
-to open when the volume is mounted.  See L<bless(8)>.
-
-=item
-
-All files in the volume are set to be world-readable, only writable
-by the owner, and world-executable when appropriate.  All other
-permissions bits are cleared.
-
-=item
-
-When possible, disk images are created without any partition tables.  This
-is what L<hdiutil(1)> refers to as I<-layout NONE>, and saves a handful of
-kilobytes.  The alternative, I<SPUD>, contains a partition table that
-is not terribly handy on disk images that are not intended to represent any
-physical disk.
-
-=item
-
-Read-write images are created with journaling off.  Any read-write image
-created by this tool is expected to be transient, and the goal of this tool
-is to create images which consume a minimum of space.
-
-=back
-
-=head1 EXAMPLE
-
-pkg-dmg --source /Applications/DeerPark.app --target ~/DeerPark.dmg
-  --sourcefile --volname DeerPark --icon ~/DeerPark.icns
-  --mkdir /.background
-  --copy DeerParkBackground.png:/.background/background.png
-  --copy DeerParkDSStore:/.DS_Store
-  --symlink /Applications:"/Drag to here"
-
-=head1 REQUIREMENTS
-
-I<pkg-dmg> has been tested with Mac OS X releases 10.2 ("Jaguar")
-through 10.4 ("Tiger").  Certain adjustments to behavior are made
-depending on the host system's release.  Mac OS X 10.3 ("Panther") or
-later are recommended.
-
-=head1 LICENSE
-
-MPL 2.
-
-=head1 AUTHOR
-
-Mark Mentovai
-
-=head1 SEE ALSO
-
-L<bless(8)>, L<diskutil(8)>, L<hdid(8)>, L<hdiutil(1)>, L<Rez(1)>,
-L<rsync(1)>, L<SetFile(1)>
-
-=cut
-
-use Fcntl;
-use POSIX;
-use Getopt::Long;
-
-sub argumentEscape(@);
-sub cleanupDie($);
-sub command(@);
-sub commandInternal($@);
-sub commandInternalVerbosity($$@);
-sub commandOutput(@);
-sub commandOutputVerbosity($@);
-sub commandVerbosity($@);
-sub copyFiles($@);
-sub diskImageMaker($$$$$$$$);
-sub giveExtension($$);
-sub hdidMountImage($@);
-sub isFormatCompressed($);
-sub licenseMaker($$);
-sub pathSplit($);
-sub setAttributes($@);
-sub trapSignal($);
-sub usage();
-
-# Variables used as globals
-my(@gCleanup, %gConfig, $gDarwinMajor, $gDryRun, $gVerbosity);
-
-# Use the commands by name if they're expected to be in the user's
-# $PATH (/bin:/sbin:/usr/bin:/usr/sbin).  Otherwise, go by absolute
-# path.  These may be overridden with --config.
-%gConfig = ('cmd_bless'          => 'bless',
-            'cmd_chmod'          => 'chmod',
-            'cmd_diskutil'       => 'diskutil',
-            'cmd_du'             => 'du',
-            'cmd_hdid'           => 'hdid',
-            'cmd_hdiutil'        => 'hdiutil',
-            'cmd_mkdir'          => 'mkdir',
-            'cmd_mktemp'         => 'mktemp',
-            'cmd_Rez'            => 'Rez',
-            'cmd_rm'             => 'rm',
-            'cmd_rsync'          => 'rsync',
-            'cmd_SetFile'        => 'SetFile',
-
-            # create_directly indicates whether hdiutil create supports
-            # -srcfolder and -srcdevice.  It does on >= 10.3 (Panther).
-            # This is fixed up for earlier systems below.  If false,
-            # hdiutil create is used to create empty disk images that
-            # are manually filled.
-            'create_directly'    => 1,
-
-            # If hdiutil attach -mountpoint exists, use it to avoid
-            # mounting disk images in the default /Volumes.  This reduces
-            # the likelihood that someone will notice a mounted image and
-            # interfere with it.  Only available on >= 10.3 (Panther),
-            # fixed up for earlier systems below.
-            #
-            # This is presently turned off for all systems, because there
-            # is an infrequent synchronization problem during ejection.
-            # diskutil eject might return before the image is actually
-            # unmounted.  If pkg-dmg then attempts to clean up its
-            # temporary directory, it could remove items from a read-write
-            # disk image or attempt to remove items from a read-only disk
-            # image (or a read-only item from a read-write image) and fail,
-            # causing pkg-dmg to abort.  This problem is experienced
-            # under Tiger, which appears to eject asynchronously where
-            # previous systems treated it as a synchronous operation.
-            # Using hdiutil attach -mountpoint didn't always keep images
-            # from showing up on the desktop anyway.
-            'hdiutil_mountpoint' => 0,
-
-            # hdiutil makehybrid results in optimized disk images that
-            # consume less space and mount more quickly.  Use it when
-            # it's available, but that's only on >= 10.3 (Panther).
-            # If false, hdiutil create is used instead.  Fixed up for
-            # earlier systems below.
-            'makehybrid'         => 1,
-
-            # hdiutil create doesn't allow specifying a folder to open
-            # at volume mount time, so those images are mounted and
-            # their root folders made holy with bless -openfolder.  But
-            # only on >= 10.3 (Panther).  Earlier systems are out of luck.
-            # Even on Panther, bless refuses to run unless root.
-            # Fixed up below.
-            'openfolder_bless'   => 1,
-
-            # It's possible to save a few more kilobytes by including the
-            # partition only without any partition table in the image.
-            # This is a good idea on any system, so turn this option off.
-            #
-            # Except it's buggy.  "-layout NONE" seems to be creating
-            # disk images with more data than just the partition table
-            # stripped out.  You might wind up losing the end of the
-            # filesystem - the last file (or several) might be incomplete.
-            'partition_table'    => 1,
-
-            # To create a partition table-less image from something
-            # created by makehybrid, the hybrid image needs to be
-            # mounted and a new image made from the device associated
-            # with the relevant partition.  This requires >= 10.4
-            # (Tiger), presumably because earlier systems have
-            # problems creating images from devices themselves attached
-            # to images.  If this is false, makehybrid images will
-            # have partition tables, regardless of the partition_table
-            # setting.  Fixed up for earlier systems below.
-            'recursive_access'   => 1);
-
-# --verbosity
-$gVerbosity = 2;
-
-# --dry-run
-$gDryRun = 0;
-
-# %gConfig fix-ups based on features and bugs present in certain releases.
-my($ignore, $uname_r, $uname_s);
-($uname_s, $ignore, $uname_r, $ignore, $ignore) = POSIX::uname();
-if($uname_s eq 'Darwin') {
-  ($gDarwinMajor, $ignore) = split(/\./, $uname_r, 2);
-
-  # $major is the Darwin major release, which for our purposes, is 4 higher
-  # than the interesting digit in a Mac OS X release.
-  if($gDarwinMajor <= 6) {
-    # <= 10.2 (Jaguar)
-    # hdiutil create does not support -srcfolder or -srcdevice
-    $gConfig{'create_directly'} = 0;
-    # hdiutil attach does not support -mountpoint
-    $gConfig{'hdiutil_mountpoint'} = 0;
-    # hdiutil mkhybrid does not exist
-    $gConfig{'makehybrid'} = 0;
-  }
-  if($gDarwinMajor <= 7) {
-    # <= 10.3 (Panther)
-    # Can't mount a disk image and then make a disk image from the device
-    $gConfig{'recursive_access'} = 0;
-    # bless does not support -openfolder on 10.2 (Jaguar) and must run
-    # as root under 10.3 (Panther)
-    $gConfig{'openfolder_bless'} = 0;
-  }
-}
-else {
-  # If it's not Mac OS X, just assume all of those good features are
-  # available.  They're not, but things will fail long before they
-  # have a chance to make a difference.
-  #
-  # Now, if someone wanted to document some of these private formats...
-  print STDERR ($0.": warning, not running on Mac OS X, ".
-   "this could be interesting.\n");
-}
-
-# Non-global variables used in Getopt
-my(@attributes, @copyFiles, @createSymlinks, $iconFile, $idme, $licenseFile,
- @makeDirs, $outputFormat, @resourceFiles, $sourceFile, $sourceFolder,
- $targetImage, $tempDir, $volumeName);
-
-# --format
-$outputFormat = 'UDBZ';
-
-# --idme
-$idme = 0;
-
-# --sourcefile
-$sourceFile = 0;
-
-# Leaving this might screw up the Apple tools.
-delete $ENV{'NEXT_ROOT'};
-
-# This script can get pretty messy, so trap a few signals.
-$SIG{'INT'} = \&trapSignal;
-$SIG{'HUP'} = \&trapSignal;
-$SIG{'TERM'} = \&trapSignal;
-
-Getopt::Long::Configure('pass_through');
-GetOptions('source=s'    => \$sourceFolder,
-           'target=s'    => \$targetImage,
-           'volname=s'   => \$volumeName,
-           'format=s'    => \$outputFormat,
-           'tempdir=s'   => \$tempDir,
-           'mkdir=s'     => \@makeDirs,
-           'copy=s'      => \@copyFiles,
-           'symlink=s'   => \@createSymlinks,
-           'license=s'   => \$licenseFile,
-           'resource=s'  => \@resourceFiles,
-           'icon=s'      => \$iconFile,
-           'attribute=s' => \@attributes,
-           'idme'        => \$idme,
-           'sourcefile'  => \$sourceFile,
-           'verbosity=i' => \$gVerbosity,
-           'dry-run'     => \$gDryRun,
-           'config=s'    => \%gConfig); # "hidden" option not in usage()
-
-if(@ARGV) {
-  # All arguments are parsed by Getopt
-  usage();
-  exit(1);
-}
-
-if($gVerbosity<0 || $gVerbosity>2) {
-  usage();
-  exit(1);
-}
-
-if(!defined($sourceFolder) || $sourceFolder eq '' ||
- !defined($targetImage) || $targetImage eq '') {
-  # --source and --target are required arguments
-  usage();
-  exit(1);
-}
-
-# Make sure $sourceFolder doesn't contain trailing slashes.  It messes with
-# rsync.
-while(substr($sourceFolder, -1) eq '/') {
-  chop($sourceFolder);
-}
-
-if(!defined($volumeName)) {
-  # Default volumeName is the name of the source directory.
-  my(@components);
-  @components = pathSplit($sourceFolder);
-  $volumeName = pop(@components);
-}
-
-my(@tempDirComponents, $targetImageFilename);
-@tempDirComponents = pathSplit($targetImage);
-$targetImageFilename = pop(@tempDirComponents);
-
-if(defined($tempDir)) {
-  @tempDirComponents = pathSplit($tempDir);
-}
-else {
-  # Default tempDir is the same directory as what is specified for
-  # targetImage
-  $tempDir = join('/', @tempDirComponents);
-}
-
-# Ensure that the path of the target image has a suitable extension.  If
-# it didn't, hdiutil would add one, and we wouldn't be able to find the
-# file.
-#
-# Note that $targetImageFilename is not being reset.  This is because it's
-# used to build other names below, and we don't need to be adding all sorts
-# of extra unnecessary extensions to the name.
-my($originalTargetImage, $requiredExtension);
-$originalTargetImage = $targetImage;
-if($outputFormat eq 'UDSP') {
-  $requiredExtension = '.sparseimage';
-}
-else {
-  $requiredExtension = '.dmg';
-}
-$targetImage = giveExtension($originalTargetImage, $requiredExtension);
-
-if($targetImage ne $originalTargetImage) {
-  print STDERR ($0.": warning: target image extension is being added\n");
-  print STDERR ('  The new filename is '.
-   giveExtension($targetImageFilename,$requiredExtension)."\n");
-}
-
-# Make a temporary directory in $tempDir for our own nefarious purposes.
-my(@output, $tempSubdir, $tempSubdirTemplate);
-$tempSubdirTemplate=join('/', @tempDirComponents,
- 'pkg-dmg.'.$$.'.XXXXXXXX');
-if(!(@output = commandOutput($gConfig{'cmd_mktemp'}, '-d',
- $tempSubdirTemplate)) || $#output != 0) {
-  cleanupDie('mktemp failed');
-}
-
-if($gDryRun) {
-  (@output)=($tempSubdirTemplate);
-}
-
-($tempSubdir) = @output;
-
-push(@gCleanup,
- sub {commandVerbosity(0, $gConfig{'cmd_rm'}, '-rf', $tempSubdir);});
-
-my($tempMount, $tempRoot, @tempsToMake);
-$tempRoot = $tempSubdir.'/stage';
-$tempMount = $tempSubdir.'/mount';
-push(@tempsToMake, $tempRoot);
-if($gConfig{'hdiutil_mountpoint'}) {
-  push(@tempsToMake, $tempMount);
-}
-
-if(command($gConfig{'cmd_mkdir'}, @tempsToMake) != 0) {
-  cleanupDie('mkdir tempRoot/tempMount failed');
-}
-
-# This cleanup object is not strictly necessary, because $tempRoot is inside
-# of $tempSubdir, but the rest of the script relies on this object being
-# on the cleanup stack and expects to remove it.
-push(@gCleanup,
- sub {commandVerbosity(0, $gConfig{'cmd_rm'}, '-rf', $tempRoot);});
-
-# If $sourceFile is true, it means that $sourceFolder is to be treated as
-# a file and placed as a file within the volume root, as opposed to being
-# treated as the volume root itself.  rsync will do this by default, if no
-# trailing '/' is present.  With a trailing '/', $sourceFolder becomes
-# $tempRoot, instead of becoming an entry in $tempRoot.
-if(command($gConfig{'cmd_rsync'}, '-a', '--copy-unsafe-links',
- $sourceFolder.($sourceFile?'':'/'),$tempRoot) != 0) {
-  cleanupDie('rsync failed');
-}
-
-if(@makeDirs) {
-  my($makeDir, @tempDirsToMake);
-  foreach $makeDir (@makeDirs) {
-    if($makeDir =~ /^\//) {
-      push(@tempDirsToMake, $tempRoot.$makeDir);
-    }
-    else {
-      push(@tempDirsToMake, $tempRoot.'/'.$makeDir);
-    }
-  }
-  if(command($gConfig{'cmd_mkdir'}, '-p', @tempDirsToMake) != 0) {
-    cleanupDie('mkdir failed');
-  }
-}
-
-# copy files and/or create symlinks
-copyFiles($tempRoot, 'copy', @copyFiles);
-copyFiles($tempRoot, 'symlink', @createSymlinks);
-
-if($gConfig{'create_directly'}) {
-  # If create_directly is false, the contents will be rsynced into a
-  # disk image and they would lose their attributes.
-  setAttributes($tempRoot, @attributes);
-}
-
-if(defined($iconFile)) {
-  if(command($gConfig{'cmd_rsync'}, '-a', '--copy-unsafe-links', $iconFile,
-   $tempRoot.'/.VolumeIcon.icns') != 0) {
-    cleanupDie('rsync failed for volume icon');
-  }
-
-  # It's pointless to set the attributes of the root when diskutil create
-  # -srcfolder is being used.  In that case, the attributes will be set
-  # later, after the image is already created.
-  if(isFormatCompressed($outputFormat) &&
-   (command($gConfig{'cmd_SetFile'}, '-a', 'C', $tempRoot) != 0)) {
-    cleanupDie('SetFile failed');
-  }
-}
-
-if(command($gConfig{'cmd_chmod'}, '-R', 'a+rX,a-st,u+w,go-w',
- $tempRoot) != 0) {
-  cleanupDie('chmod failed');
-}
-
-my($unflattenable);
-if(isFormatCompressed($outputFormat)) {
-  $unflattenable = 1;
-}
-else {
-  $unflattenable = 0;
-}
-
-diskImageMaker($tempRoot, $targetImage, $outputFormat, $volumeName,
- $tempSubdir, $tempMount, $targetImageFilename, defined($iconFile));
-
-if(defined($licenseFile) && $licenseFile ne '') {
-  my($licenseResource);
-  $licenseResource = $tempSubdir.'/license.r';
-  if(!licenseMaker($licenseFile, $licenseResource)) {
-    cleanupDie('licenseMaker failed');
-  }
-  push(@resourceFiles, $licenseResource);
-  # Don't add a cleanup object because licenseResource is in tempSubdir.
-}
-
-if(@resourceFiles) {
-  # Add resources, such as a license agreement.
-
-  # Only unflatten read-only and compressed images.  It's not supported
-  # on other image times.
-  if($unflattenable &&
-   (command($gConfig{'cmd_hdiutil'}, 'unflatten', $targetImage)) != 0) {
-    cleanupDie('hdiutil unflatten failed');
-  }
-  # Don't push flatten onto the cleanup stack.  If we fail now, we'll be
-  # removing $targetImage anyway.
-
-  # Type definitions come from Carbon.r.
-  if(command($gConfig{'cmd_Rez'}, 'Carbon.r', @resourceFiles, '-a', '-o',
-   $targetImage) != 0) {
-    cleanupDie('Rez failed');
-  }
-
-  # Flatten.  This merges the resource fork into the data fork, so no
-  # special encoding is needed to transfer the file.
-  if($unflattenable &&
-   (command($gConfig{'cmd_hdiutil'}, 'flatten', $targetImage)) != 0) {
-    cleanupDie('hdiutil flatten failed');
-  }
-}
-
-# $tempSubdir is no longer needed.  It's buried on the stack below the
-# rm of the fresh image file.  Splice in this fashion is equivalent to
-# pop-save, pop, push-save.
-splice(@gCleanup, -2, 1);
-# No need to remove licenseResource separately, it's in tempSubdir.
-if(command($gConfig{'cmd_rm'}, '-rf', $tempSubdir) != 0) {
-  cleanupDie('rm -rf tempSubdir failed');
-}
-
-if($idme) {
-  if(command($gConfig{'cmd_hdiutil'}, 'internet-enable', '-yes',
-   $targetImage) != 0) {
-    cleanupDie('hdiutil internet-enable failed');
-  }
-}
-
-# Done.
-
-exit(0);
-
-# argumentEscape(@arguments)
-#
-# Takes a list of @arguments and makes them shell-safe.
-sub argumentEscape(@) {
-  my(@arguments);
-  @arguments = @_;
-  my($argument, @argumentsOut);
-  foreach $argument (@arguments) {
-    $argument =~ s%([^A-Za-z0-9_\-/.=+,])%\\$1%g;
-    push(@argumentsOut, $argument);
-  }
-  return @argumentsOut;
-}
-
-# cleanupDie($message)
-#
-# Displays $message as an error message, and then runs through the
-# @gCleanup stack, performing any cleanup operations needed before
-# exiting.  Does not return, exits with exit status 1.
-sub cleanupDie($) {
-  my($message);
-  ($message) = @_;
-  print STDERR ($0.': '.$message.(@gCleanup?' (cleaning up)':'')."\n");
-  while(@gCleanup) {
-    my($subroutine);
-    $subroutine = pop(@gCleanup);
-    &$subroutine;
-  }
-  exit(1);
-}
-
-# command(@arguments)
-#
-# Runs the specified command at the verbosity level defined by $gVerbosity.
-# Returns nonzero on failure, returning the exit status if appropriate.
-# Discards command output.
-sub command(@) {
-  my(@arguments);
-  @arguments = @_;
-  return commandVerbosity($gVerbosity,@arguments);
-}
-
-# commandInternal($command, @arguments)
-#
-# Runs the specified internal command at the verbosity level defined by
-# $gVerbosity.
-# Returns zero(!) on failure, because commandInternal is supposed to be a
-# direct replacement for the Perl system call wrappers, which, unlike shell
-# commands and C equivalent system calls, return true (instead of 0) to
-# indicate success.
-sub commandInternal($@) {
-  my(@arguments, $command);
-  ($command, @arguments) = @_;
-  return commandInternalVerbosity($gVerbosity, $command, @arguments);
-}
-
-# commandInternalVerbosity($verbosity, $command, @arguments)
-#
-# Run an internal command, printing a bogus command invocation message if
-# $verbosity is true.
-#
-# If $command is unlink:
-# Removes the files specified by @arguments.  Wraps unlink.
-#
-# If $command is symlink:
-# Creates the symlink specified by @arguments. Wraps symlink.
-sub commandInternalVerbosity($$@) {
-  my(@arguments, $command, $verbosity);
-  ($verbosity, $command, @arguments) = @_;
-  if($command eq 'unlink') {
-    if($verbosity || $gDryRun) {
-      print(join(' ', 'rm', '-f', argumentEscape(@arguments))."\n");
-    }
-    if($gDryRun) {
-      return $#arguments+1;
-    }
-    return unlink(@arguments);
-  }
-  elsif($command eq 'symlink') {
-    if($verbosity || $gDryRun) {
-      print(join(' ', 'ln', '-s', argumentEscape(@arguments))."\n");
-    }
-    if($gDryRun) {
-      return 1;
-    }
-    my($source, $target);
-    ($source, $target) = @arguments;
-    return symlink($source, $target);
-  }
-}
-
-# commandOutput(@arguments)
-#
-# Runs the specified command at the verbosity level defined by $gVerbosity.
-# Output is returned in an array of lines.  undef is returned on failure.
-# The exit status is available in $?.
-sub commandOutput(@) {
-  my(@arguments);
-  @arguments = @_;
-  return commandOutputVerbosity($gVerbosity, @arguments);
-}
-
-# commandOutputVerbosity($verbosity, @arguments)
-#
-# Runs the specified command at the verbosity level defined by the
-# $verbosity argument.  Output is returned in an array of lines.  undef is
-# returned on failure.  The exit status is available in $?.
-#
-# If an error occurs in fork or exec, an error message is printed to
-# stderr and undef is returned.
-#
-# If $verbosity is 0, the command invocation is not printed, and its
-# stdout is not echoed back to stdout.
-#
-# If $verbosity is 1, the command invocation is printed.
-#
-# If $verbosity is 2, the command invocation is printed and the output
-# from stdout is echoed back to stdout.
-#
-# Regardless of $verbosity, stderr is left connected.
-sub commandOutputVerbosity($@) {
-  my(@arguments, $verbosity);
-  ($verbosity, @arguments) = @_;
-  my($pid);
-  if($verbosity || $gDryRun) {
-    print(join(' ', argumentEscape(@arguments))."\n");
-  }
-  if($gDryRun) {
-    return(1);
-  }
-  if (!defined($pid = open(*COMMAND, '-|'))) {
-    printf STDERR ($0.': fork: '.$!."\n");
-    return undef;
-  }
-  elsif ($pid) {
-    # parent
-    my(@lines);
-    while(!eof(*COMMAND)) {
-      my($line);
-      chop($line = <COMMAND>);
-      if($verbosity > 1) {
-        print($line."\n");
-      }
-      push(@lines, $line);
-    }
-    close(*COMMAND);
-    if ($? == -1) {
-      printf STDERR ($0.': fork: '.$!."\n");
-      return undef;
-    }
-    elsif ($? & 127) {
-      printf STDERR ($0.': exited on signal '.($? & 127).
-       ($? & 128 ? ', core dumped' : '')."\n");
-      return undef;
-    }
-    return @lines;
-  }
-  else {
-    # child; this form of exec is immune to shell games
-    if(!exec {$arguments[0]} (@arguments)) {
-      printf STDERR ($0.': exec: '.$!."\n");
-      exit(-1);
-    }
-  }
-}
-
-# commandVerbosity($verbosity, @arguments)
-#
-# Runs the specified command at the verbosity level defined by the
-# $verbosity argument.  Returns nonzero on failure, returning the exit
-# status if appropriate.  Discards command output.
-sub commandVerbosity($@) {
-  my(@arguments, $verbosity);
-  ($verbosity, @arguments) = @_;
-  if(!defined(commandOutputVerbosity($verbosity, @arguments))) {
-    return -1;
-  }
-  return $?;
-}
-
-# copyFiles($tempRoot, $method, @arguments)
-#
-# Copies files or create symlinks in the disk image.
-# See --copy and --symlink descriptions for details.
-# If $method is 'copy', @arguments are interpreted as source:target, if $method
-# is 'symlink', @arguments are interpreted as symlink:target.
-sub copyFiles($@) {
-  my(@fileList, $method, $tempRoot);
-  ($tempRoot, $method, @fileList) = @_;
-  my($file, $isSymlink);
-  $isSymlink = ($method eq 'symlink');
-  foreach $file (@fileList) {
-    my($source, $target);
-    ($source, $target) = split(/:/, $file);
-    if(!defined($target) and $isSymlink) {
-      # empty symlink targets would result in an invalid target and fail,
-      # but they shall be interpreted as "like source path, but inside dmg"
-      $target = $source;
-    }
-    if(!defined($target)) {
-      $target = $tempRoot;
-    }
-    elsif($target =~ /^\//) {
-      $target = $tempRoot.$target;
-    }
-    else {
-      $target = $tempRoot.'/'.$target;
-    }
-
-    my($success);
-    if($isSymlink) {
-      $success = commandInternal('symlink', $source, $target);
-    }
-    else {
-      $success = !command($gConfig{'cmd_rsync'}, '-a', '--copy-unsafe-links',
-                          $source, $target);
-    }
-    if(!$success) {
-      cleanupDie('copyFiles failed for method '.$method);
-    }
-  }
-}
-
-# diskImageMaker($source, $destination, $format, $name, $tempDir, $tempMount,
-#  $baseName, $setRootIcon)
-#
-# Creates a disk image in $destination of format $format corresponding to the
-# source directory $source.  $name is the volume name.  $tempDir is a good
-# place to write temporary files, which should be empty (aside from the other
-# things that this script might create there, like stage and mount).
-# $tempMount is a mount point for temporary disk images.  $baseName is the
-# name of the disk image, and is presently unused.  $setRootIcon is true if
-# a volume icon was added to the staged $source and indicates that the
-# custom volume icon bit on the volume root needs to be set.
-sub diskImageMaker($$$$$$$$) {
-  my($baseName, $destination, $format, $name, $setRootIcon, $source,
-   $tempDir, $tempMount);
-  ($source, $destination, $format, $name, $tempDir, $tempMount,
-   $baseName, $setRootIcon) = @_;
-  if(isFormatCompressed($format)) {
-    my($uncompressedImage);
-
-    if($gConfig{'makehybrid'}) {
-      my($hybridImage);
-      $hybridImage = giveExtension($tempDir.'/hybrid', '.dmg');
-
-      if(command($gConfig{'cmd_hdiutil'}, 'makehybrid', '-hfs',
-       '-hfs-volume-name', $name, '-hfs-openfolder', $source, '-ov',
-       $source, '-o', $hybridImage) != 0) {
-        cleanupDie('hdiutil makehybrid failed');
-      }
-
-      $uncompressedImage = $hybridImage;
-
-      # $source is no longer needed and will be removed before anything
-      # else can fail.  splice in this form is the same as pop/push.
-      splice(@gCleanup, -1, 1,
-       sub {commandInternalVerbosity(0, 'unlink', $hybridImage);});
-
-      if(command($gConfig{'cmd_rm'}, '-rf', $source) != 0) {
-        cleanupDie('rm -rf failed');
-      }
-
-      if(!$gConfig{'partition_table'} && $gConfig{'recursive_access'}) {
-        # Even if we do want to create disk images without partition tables,
-        # it's impossible unless recursive_access is set.
-        my($rootDevice, $partitionDevice, $partitionMountPoint);
-
-        if(!(($rootDevice, $partitionDevice, $partitionMountPoint) =
-         hdidMountImage($tempMount, '-readonly', $hybridImage))) {
-          cleanupDie('hdid mount failed');
-        }
-
-        push(@gCleanup, sub {commandVerbosity(0,
-         $gConfig{'cmd_diskutil'}, 'eject', $rootDevice);});
-
-        my($udrwImage);
-        $udrwImage = giveExtension($tempDir.'/udrw', '.dmg');
-
-        if(command($gConfig{'cmd_hdiutil'}, 'create', '-format', 'UDRW',
-         '-ov', '-srcdevice', $partitionDevice, $udrwImage) != 0) {
-          cleanupDie('hdiutil create failed');
-        }
-
-        $uncompressedImage = $udrwImage;
-
-        # Going to eject before anything else can fail.  Get the eject off
-        # the stack.
-        pop(@gCleanup);
-
-        # $hybridImage will be removed soon, but until then, it needs to
-        # stay on the cleanup stack.  It needs to wait until after
-        # ejection.  $udrwImage is staying around.  Make it appear as
-        # though it's been done before $hybridImage.
-        #
-        # splice in this form is the same as popping one element to
-        # @tempCleanup and pushing the subroutine.
-        my(@tempCleanup);
-        @tempCleanup = splice(@gCleanup, -1, 1,
-         sub {commandInternalVerbosity(0, 'unlink', $udrwImage);});
-        push(@gCleanup, @tempCleanup);
-
-        if(command($gConfig{'cmd_diskutil'}, 'eject', $rootDevice) != 0) {
-          cleanupDie('diskutil eject failed');
-        }
-
-        # Pop unlink of $uncompressedImage
-        pop(@gCleanup);
-
-        if(commandInternal('unlink', $hybridImage) != 1) {
-          cleanupDie('unlink hybridImage failed: '.$!);
-        }
-      }
-    }
-    else {
-      # makehybrid is not available, fall back to making a UDRW and
-      # converting to a compressed image.  It ought to be possible to
-      # create a compressed image directly, but those come out far too
-      # large (journaling?) and need to be read-write to fix up the
-      # volume icon anyway.  Luckily, we can take advantage of a single
-      # call back into this function.
-      my($udrwImage);
-      $udrwImage = giveExtension($tempDir.'/udrw', '.dmg');
-
-      diskImageMaker($source, $udrwImage, 'UDRW', $name, $tempDir,
-       $tempMount, $baseName, $setRootIcon);
-
-      # The call back into diskImageMaker already removed $source.
-
-      $uncompressedImage = $udrwImage;
-    }
-
-    # The uncompressed disk image is now in its final form.  Compress it.
-    # Jaguar doesn't support hdiutil convert -ov, but it always allows
-    # overwriting.
-    # bzip2-compressed UDBZ images can only be created and mounted on 10.4
-    # and later.  The bzip2-level imagekey is only effective when creating
-    # images in 10.5.  In 10.4, bzip2-level is harmlessly ignored, and the
-    # default value of 1 is always used.
-    if(command($gConfig{'cmd_hdiutil'}, 'convert', '-format', $format,
-     '-imagekey', ($format eq 'UDBZ' ? 'bzip2-level=9' : 'zlib-level=9'),
-     (defined($gDarwinMajor) && $gDarwinMajor <= 6 ? () : ('-ov')),
-     $uncompressedImage, '-o', $destination) != 0) {
-      cleanupDie('hdiutil convert failed');
-    }
-
-    # $uncompressedImage is going to be unlinked before anything else can
-    # fail.  splice in this form is the same as pop/push.
-    splice(@gCleanup, -1, 1,
-     sub {commandInternalVerbosity(0, 'unlink', $destination);});
-
-    if(commandInternal('unlink', $uncompressedImage) != 1) {
-      cleanupDie('unlink uncompressedImage failed: '.$!);
-    }
-
-    # At this point, the only thing that the compressed block has added to
-    # the cleanup stack is the removal of $destination.  $source has already
-    # been removed, and its cleanup entry has been removed as well.
-  }
-  elsif($format eq 'UDRW' || $format eq 'UDSP') {
-    my(@extraArguments);
-    if(!$gConfig{'partition_table'}) {
-      @extraArguments = ('-layout', 'NONE');
-    }
-
-    if($gConfig{'create_directly'}) {
-      # Use -fs HFS+ to suppress the journal.
-      if(command($gConfig{'cmd_hdiutil'}, 'create', '-format', $format,
-       @extraArguments, '-fs', 'HFS+', '-volname', $name,
-       '-ov', '-srcfolder', $source, $destination) != 0) {
-        cleanupDie('hdiutil create failed');
-      }
-
-      # $source is no longer needed and will be removed before anything
-      # else can fail.  splice in this form is the same as pop/push.
-      splice(@gCleanup, -1, 1,
-       sub {commandInternalVerbosity(0, 'unlink', $destination);});
-
-      if(command($gConfig{'cmd_rm'}, '-rf', $source) != 0) {
-        cleanupDie('rm -rf failed');
-      }
-    }
-    else {
-      # hdiutil create does not support -srcfolder or -srcdevice, it only
-      # knows how to create blank images.  Figure out how large an image
-      # is needed, create it, and fill it.  This is needed for Jaguar.
-
-      # Use native block size for hdiutil create -sectors.
-      delete $ENV{'BLOCKSIZE'};
-
-      my(@duOutput, $ignore, $sizeBlocks, $sizeOverhead, $sizeTotal, $type);
-      if(!(@output = commandOutput($gConfig{'cmd_du'}, '-s', $tempRoot)) ||
-       $? != 0) {
-        cleanupDie('du failed');
-      }
-      ($sizeBlocks, $ignore) = split(' ', $output[0], 2);
-
-      # The filesystem itself takes up 152 blocks of its own blocks for the
-      # filesystem up to 8192 blocks, plus 64 blocks for every additional
-      # 4096 blocks or portion thereof.
-      $sizeOverhead = 152 + 64 * POSIX::ceil(
-       (($sizeBlocks - 8192) > 0) ? (($sizeBlocks - 8192) / (4096 - 64)) : 0);
-
-      # The number of blocks must be divisible by 8.
-      my($mod);
-      if($mod = ($sizeOverhead % 8)) {
-        $sizeOverhead += 8 - $mod;
-      }
-
-      # sectors is taken as the size of a disk, not a filesystem, so the
-      # partition table eats into it.
-      if($gConfig{'partition_table'}) {
-        $sizeOverhead += 80;
-      }
-
-      # That was hard.  Leave some breathing room anyway.  Use 1024 sectors
-      # (512kB).  These read-write images wouldn't be useful if they didn't
-      # have at least a little free space.
-      $sizeTotal = $sizeBlocks + $sizeOverhead + 1024;
-
-      # Minimum sizes - these numbers are larger on Jaguar than on later
-      # systems.  Just use the Jaguar numbers, since it's unlikely to wind
-      # up here on any other release.
-      if($gConfig{'partition_table'} && $sizeTotal < 8272) {
-        $sizeTotal = 8272;
-      }
-      if(!$gConfig{'partition_table'} && $sizeTotal < 8192) {
-        $sizeTotal = 8192;
-      }
-
-      # hdiutil create without -srcfolder or -srcdevice will not accept
-      # -format.  It uses -type.  Fortunately, the two supported formats
-      # here map directly to the only two supported types.
-      if ($format eq 'UDSP') {
-        $type = 'SPARSE';
-      }
-      else {
-        $type = 'UDIF';
-      }
-
-      if(command($gConfig{'cmd_hdiutil'}, 'create', '-type', $type,
-       @extraArguments, '-fs', 'HFS+', '-volname', $name,
-       '-ov', '-sectors', $sizeTotal, $destination) != 0) {
-        cleanupDie('hdiutil create failed');
-      }
-
-      push(@gCleanup,
-       sub {commandInternalVerbosity(0, 'unlink', $destination);});
-
-      # The rsync will occur shortly.
-    }
-
-    my($mounted, $rootDevice, $partitionDevice, $partitionMountPoint);
-
-    $mounted=0;
-    if(!$gConfig{'create_directly'} || $gConfig{'openfolder_bless'} ||
-     $setRootIcon) {
-      # The disk image only needs to be mounted if:
-      #  create_directly is false, because the content needs to be copied
-      #  openfolder_bless is true, because bless -openfolder needs to run
-      #  setRootIcon is true, because the root needs its attributes set.
-      if(!(($rootDevice, $partitionDevice, $partitionMountPoint) =
-       hdidMountImage($tempMount, $destination))) {
-        cleanupDie('hdid mount failed');
-      }
-
-      $mounted=1;
-
-      push(@gCleanup, sub {commandVerbosity(0,
-       $gConfig{'cmd_diskutil'}, 'eject', $rootDevice);});
-    }
-
-    if(!$gConfig{'create_directly'}) {
-      # Couldn't create and copy directly in one fell swoop.  Now that
-      # the volume is mounted, copy the files.  --copy-unsafe-links is
-      # unnecessary since it was used to copy everything to the staging
-      # area.  There can be no more unsafe links.
-      if(command($gConfig{'cmd_rsync'}, '-a',
-       $source.'/',$partitionMountPoint) != 0) {
-        cleanupDie('rsync to new volume failed');
-      }
-
-      # We need to get the rm -rf of $source off the stack, because it's
-      # being cleaned up here.  There are two items now on top of it:
-      # removing the target image and, above that, ejecting it.  Splice it
-      # out.
-      my(@tempCleanup);
-      @tempCleanup = splice(@gCleanup, -2);
-      # The next splice is the same as popping once and pushing @tempCleanup.
-      splice(@gCleanup, -1, 1, @tempCleanup);
-
-      if(command($gConfig{'cmd_rm'}, '-rf', $source) != 0) {
-        cleanupDie('rm -rf failed');
-      }
-    }
-
-    if($gConfig{'openfolder_bless'}) {
-      # On Tiger, the bless docs say to use --openfolder, but only
-      # --openfolder is accepted on Panther.  Tiger takes it with a single
-      # dash too.  Jaguar is out of luck.
-      if(command($gConfig{'cmd_bless'}, '-openfolder',
-       $partitionMountPoint) != 0) {
-        cleanupDie('bless failed');
-      }
-    }
-
-    setAttributes($partitionMountPoint, @attributes);
-
-    if($setRootIcon) {
-      # When "hdiutil create -srcfolder" is used, the root folder's
-      # attributes are not copied to the new volume.  Fix up.
-
-      if(command($gConfig{'cmd_SetFile'}, '-a', 'C',
-       $partitionMountPoint) != 0) {
-        cleanupDie('SetFile failed');
-      }
-    }
-
-    if($mounted) {
-      # Pop diskutil eject
-      pop(@gCleanup);
-
-      if(command($gConfig{'cmd_diskutil'}, 'eject', $rootDevice) != 0) {
-        cleanupDie('diskutil eject failed');
-      }
-    }
-
-    # End of UDRW/UDSP section.  At this point, $source has been removed
-    # and its cleanup entry has been removed from the stack.
-  }
-  else {
-    cleanupDie('unrecognized format');
-    print STDERR ($0.": unrecognized format\n");
-    exit(1);
-  }
-}
-
-# giveExtension($file, $extension)
-#
-# If $file does not end in $extension, $extension is added.  The new
-# filename is returned.
-sub giveExtension($$) {
-  my($extension, $file);
-  ($file, $extension) = @_;
-  if(substr($file, -length($extension)) ne $extension) {
-    return $file.$extension;
-  }
-  return $file;
-}
-
-# hdidMountImage($mountPoint, @arguments)
-#
-# Runs the hdid command with arguments specified by @arguments.
-# @arguments may be a single-element array containing the name of the
-# disk image to mount.  Returns a three-element array, with elements
-# corresponding to:
-#  - The root device of the mounted image, suitable for ejection
-#  - The device corresponding to the mounted partition
-#  - The mounted partition's mount point
-#
-# If running on a system that supports easy mounting at points outside
-# of the default /Volumes with hdiutil attach, it is used instead of hdid,
-# and $mountPoint is used as the mount point.
-#
-# The root device will differ from the partition device when the disk
-# image contains a partition table, otherwise, they will be identical.
-#
-# If hdid fails, undef is returned.
-sub hdidMountImage($@) {
-  my(@arguments, @command, $mountPoint);
-  ($mountPoint, @arguments) = @_;
-  my(@output);
-
-  if($gConfig{'hdiutil_mountpoint'}) {
-    @command=($gConfig{'cmd_hdiutil'}, 'attach', @arguments,
-     '-mountpoint', $mountPoint);
-  }
-  else {
-    @command=($gConfig{'cmd_hdid'}, @arguments);
-  }
-
-  if(!(@output = commandOutput(@command)) ||
-   $? != 0) {
-    return undef;
-  }
-
-  if($gDryRun) {
-    return('/dev/diskX','/dev/diskXsY','/Volumes/'.$volumeName);
-  }
-
-  my($line, $restOfLine, $rootDevice);
-
-  foreach $line (@output) {
-    my($device, $mountpoint);
-    if($line !~ /^\/dev\//) {
-      # Consider only lines that correspond to /dev entries
-      next;
-    }
-    ($device, $restOfLine) = split(' ', $line, 2);
-
-    if(!defined($rootDevice) || $rootDevice eq '') {
-      # If this is the first device seen, it's the root device to be
-      # used for ejection.  Keep it.
-      $rootDevice = $device;
-    }
-
-    if($restOfLine =~ /(\/.*)/) {
-      # The first partition with a mount point is the interesting one.  It's
-      # usually Apple_HFS and usually the last one in the list, but beware of
-      # the possibility of other filesystem types and the Apple_Free partition.
-      # If the disk image contains no partition table, the partition will not
-      # have a type, so look for the mount point by looking for a slash.
-      $mountpoint = $1;
-      return($rootDevice, $device, $mountpoint);
-    }
-  }
-
-  # No mount point?  This is bad.  If there's a root device, eject it.
-  if(defined($rootDevice) && $rootDevice ne '') {
-    # Failing anyway, so don't care about failure
-    commandVerbosity(0, $gConfig{'cmd_diskutil'}, 'eject', $rootDevice);
-  }
-
-  return undef;
-}
-
-# isFormatCompressed($format)
-#
-# Returns true if $format corresponds to a compressed disk image format.
-# Returns false otherwise.
-sub isFormatCompressed($) {
-  my($format);
-  ($format) = @_;
-  return $format eq 'UDZO' || $format eq 'UDBZ';
-}
-
-# licenseMaker($text, $resource)
-#
-# Takes a plain text file at path $text and creates a license agreement
-# resource containing the text at path $license.  English-only, and
-# no special formatting.  This is the bare-bones stuff.  For more
-# intricate license agreements, create your own resource.
-#
-# ftp://ftp.apple.com/developer/Development_Kits/SLAs_for_UDIFs_1.0.dmg
-sub licenseMaker($$) {
-  my($resource, $text);
-  ($text, $resource) = @_;
-  if(!sysopen(*TEXT, $text, O_RDONLY)) {
-    print STDERR ($0.': licenseMaker: sysopen text: '.$!."\n");
-    return 0;
-  }
-  if(!sysopen(*RESOURCE, $resource, O_WRONLY|O_CREAT|O_EXCL)) {
-    print STDERR ($0.': licenseMaker: sysopen resource: '.$!."\n");
-    return 0;
-  }
-  print RESOURCE << '__EOT__';
-// See /System/Library/Frameworks/CoreServices.framework/Frameworks/CarbonCore.framework/Headers/Script.h for language IDs.
-data 'LPic' (5000) {
-  // Default language ID, 0 = English
-  $"0000"
-  // Number of entries in list
-  $"0001"
-
-  // Entry 1
-  // Language ID, 0 = English
-  $"0000"
-  // Resource ID, 0 = STR#/TEXT/styl 5000
-  $"0000"
-  // Multibyte language, 0 = no
-  $"0000"
-};
-
-resource 'STR#' (5000, "English") {
-  {
-    // Language (unused?) = English
-    "English",
-    // Agree
-    "Agree",
-    // Disagree
-    "Disagree",
-__EOT__
-    # This stuff needs double-quotes for interpolations to work.
-    print RESOURCE ("    // Print, ellipsis is 0xC9\n");
-    print RESOURCE ("    \"Print\xc9\",\n");
-    print RESOURCE ("    // Save As, ellipsis is 0xC9\n");
-    print RESOURCE ("    \"Save As\xc9\",\n");
-    print RESOURCE ('    // Descriptive text, curly quotes are 0xD2 and 0xD3'.
-     "\n");
-    print RESOURCE ('    "If you agree to the terms of this license '.
-     "agreement, click \xd2Agree\xd3 to access the software.  If you ".
-     "do not agree, press \xd2Disagree.\xd3\"\n");
-print RESOURCE << '__EOT__';
-  };
-};
-
-// Beware of 1024(?) byte (character?) line length limitation.  Split up long
-// lines.
-// If straight quotes are used ("), remember to escape them (\").
-// Newline is \n, to leave a blank line, use two of them.
-// 0xD2 and 0xD3 are curly double-quotes ("), 0xD4 and 0xD5 are curly
-//   single quotes ('), 0xD5 is also the apostrophe.
-data 'TEXT' (5000, "English") {
-__EOT__
-
-  while(!eof(*TEXT)) {
-    my($line);
-    chop($line = <TEXT>);
-
-    while(defined($line)) {
-      my($chunk);
-
-      # Rez doesn't care for lines longer than (1024?) characters.  Split
-      # at less than half of that limit, in case everything needs to be
-      # backwhacked.
-      if(length($line)>500) {
-        $chunk = substr($line, 0, 500);
-        $line = substr($line, 500);
-      }
-      else {
-        $chunk = $line;
-        $line = undef;
-      }
-
-      if(length($chunk) > 0) {
-        # Unsafe characters are the double-quote (") and backslash (\), escape
-        # them with backslashes.
-        $chunk =~ s/(["\\])/\\$1/g;
-
-        print RESOURCE '  "'.$chunk.'"'."\n";
-      }
-    }
-    print RESOURCE '  "\n"'."\n";
-  }
-  close(*TEXT);
-
-  print RESOURCE << '__EOT__';
-};
-
-data 'styl' (5000, "English") {
-  // Number of styles following = 1
-  $"0001"
-
-  // Style 1.  This is used to display the first two lines in bold text.
-  // Start character = 0
-  $"0000 0000"
-  // Height = 16
-  $"0010"
-  // Ascent = 12
-  $"000C"
-  // Font family = 1024 (Lucida Grande)
-  $"0400"
-  // Style bitfield, 0x1=bold 0x2=italic 0x4=underline 0x8=outline
-  // 0x10=shadow 0x20=condensed 0x40=extended
-  $"00"
-  // Style, unused?
-  $"02"
-  // Size = 12 point
-  $"000C"
-  // Color, RGB
-  $"0000 0000 0000"
-};
-__EOT__
-  close(*RESOURCE);
-
-  return 1;
-}
-
-# pathSplit($pathname)
-#
-# Splits $pathname into an array of path components.
-sub pathSplit($) {
-  my($pathname);
-  ($pathname) = @_;
-  return split(/\//, $pathname);
-}
-
-# setAttributes($root, @attributeList)
-#
-# @attributeList is an array, each element of which must be in the form
-# <a>:<file>.  <a> is a list of attributes, per SetFile.  <file> is a file
-# which is taken as relative to $root (even if it appears as an absolute
-# path.)  SetFile is called to set the attributes on each file in
-# @attributeList.
-sub setAttributes($@) {
-  my(@attributes, $root);
-  ($root, @attributes) = @_;
-  my($attribute);
-  foreach $attribute (@attributes) {
-    my($attrList, $file, @fileList, @fixedFileList);
-    ($attrList, @fileList) = split(/:/, $attribute);
-    if(!defined($attrList) || !@fileList) {
-      cleanupDie('--attribute requires <attributes>:<file>');
-    }
-    @fixedFileList=();
-    foreach $file (@fileList) {
-      if($file =~ /^\//) {
-        push(@fixedFileList, $root.$file);
-      }
-      else {
-        push(@fixedFileList, $root.'/'.$file);
-      }
-    }
-    if(command($gConfig{'cmd_SetFile'}, '-a', $attrList, @fixedFileList)) {
-      cleanupDie('SetFile failed to set attributes');
-    }
-  }
-  return;
-}
-
-sub trapSignal($) {
-  my($signalName);
-  ($signalName) = @_;
-  cleanupDie('exiting on SIG'.$signalName);
-}
-
-sub usage() {
-  print STDERR (
-"usage: pkg-dmg --source <source-folder>\n".
-"               --target <target-image>\n".
-"              [--format <format>]           (default: UDZO)\n".
-"              [--volname <volume-name>]     (default: same name as source)\n".
-"              [--tempdir <temp-dir>]        (default: same dir as target)\n".
-"              [--mkdir <directory>]         (make directory in image)\n".
-"              [--copy <source>[:<dest>]]    (extra files to add)\n".
-"              [--symlink <source>[:<dest>]] (extra symlinks to add)\n".
-"              [--license <file>]            (plain text license agreement)\n".
-"              [--resource <file>]           (flat .r files to merge)\n".
-"              [--icon <icns-file>]          (volume icon)\n".
-"              [--attribute <a>:<file>]      (set file attributes)\n".
-"              [--idme]                      (make Internet-enabled image)\n".
-"              [--sourcefile]                (treat --source as a file)\n".
-"              [--verbosity <level>]         (0, 1, 2; default=2)\n".
-"              [--dry-run]                   (print what would be done)\n");
-  return;
-}

--- a/build/virtualenv_packages.txt
+++ b/build/virtualenv_packages.txt
@@ -25,8 +25,9 @@ packages.txt:testing/mozbase/packages.tx
 objdir:build
 gyp.pth:media/webrtc/trunk/tools/gyp/pylib
 pyasn1.pth:python/pyasn1
 pyasn1_modules.pth:python/pyasn1-modules
 bitstring.pth:python/bitstring
 redo.pth:python/redo
 requests.pth:python/requests
 rsa.pth:python/rsa
+futures.pth:python/futures

--- a/config/check_macroassembler_style.py
+++ b/config/check_macroassembler_style.py
@@ -25,18 +25,18 @@ from __future__ import print_function
 import difflib
 import os
 import re
 import subprocess
 import sys
 from check_utils import get_all_toplevel_filenames
 
 architecture_independent = set([ 'generic' ])
-all_architecture_names = set([ 'x86', 'x64', 'arm', 'arm64', 'mips' ])
-all_shared_architecture_names = set([ 'x86_shared', 'arm', 'arm64', 'mips' ])
+all_architecture_names = set([ 'x86', 'x64', 'arm', 'arm64', 'mips32' ])
+all_shared_architecture_names = set([ 'x86_shared', 'arm', 'arm64', 'mips32' ])
 
 def get_normalized_signatures(signature, fileAnnot = None):
     # Remove semicolon.
     signature = signature.replace(';', ' ')
     # Normalize spaces.
     signature = re.sub(r'\s+', ' ', signature).strip()
     # Remove argument names.
     signature = re.sub(r'(?P<type>(?:[(]|,\s)[\w\s:*&]+)(?P<name>\s\w+)(?=[,)])', '\g<type>', signature)

--- a/dom/base/DOMRequest.cpp
+++ b/dom/base/DOMRequest.cpp
@@ -4,18 +4,18 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "DOMRequest.h"
 
 #include "DOMError.h"
 #include "nsThreadUtils.h"
 #include "DOMCursor.h"
-#include "nsIDOMEvent.h"
 #include "mozilla/ErrorResult.h"
+#include "mozilla/dom/Event.h"
 #include "mozilla/dom/Promise.h"
 #include "mozilla/dom/ScriptSettings.h"
 
 using mozilla::dom::AnyCallback;
 using mozilla::dom::DOMError;
 using mozilla::dom::DOMRequest;
 using mozilla::dom::DOMRequestService;
 using mozilla::dom::DOMCursor;
@@ -187,18 +187,17 @@ DOMRequest::FireDetailedError(DOMError* 
 
 void
 DOMRequest::FireEvent(const nsAString& aType, bool aBubble, bool aCancelable)
 {
   if (NS_FAILED(CheckInnerWindowCorrectness())) {
     return;
   }
 
-  nsCOMPtr<nsIDOMEvent> event;
-  NS_NewDOMEvent(getter_AddRefs(event), this, nullptr, nullptr);
+  nsRefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);
   nsresult rv = event->InitEvent(aType, aBubble, aCancelable);
   if (NS_FAILED(rv)) {
     return;
   }
 
   event->SetTrusted(true);
 
   bool dummy;

--- a/dom/base/EventSource.cpp
+++ b/dom/base/EventSource.cpp
@@ -840,22 +840,17 @@ EventSource::AnnounceConnection()
 
   mReadyState = OPEN;
 
   nsresult rv = CheckInnerWindowCorrectness();
   if (NS_FAILED(rv)) {
     return;
   }
 
-  nsCOMPtr<nsIDOMEvent> event;
-  rv = NS_NewDOMEvent(getter_AddRefs(event), this, nullptr, nullptr);
-  if (NS_FAILED(rv)) {
-    NS_WARNING("Failed to create the open event!!!");
-    return;
-  }
+  nsRefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);
 
   // it doesn't bubble, and it isn't cancelable
   rv = event->InitEvent(NS_LITERAL_STRING("open"), false, false);
   if (NS_FAILED(rv)) {
     NS_WARNING("Failed to init the open event!!!");
     return;
   }
 
@@ -905,22 +900,17 @@ EventSource::ReestablishConnection()
     return;
   }
 
   rv = CheckInnerWindowCorrectness();
   if (NS_FAILED(rv)) {
     return;
   }
 
-  nsCOMPtr<nsIDOMEvent> event;
-  rv = NS_NewDOMEvent(getter_AddRefs(event), this, nullptr, nullptr);
-  if (NS_FAILED(rv)) {
-    NS_WARNING("Failed to create the error event!!!");
-    return;
-  }
+  nsRefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);
 
   // it doesn't bubble, and it isn't cancelable
   rv = event->InitEvent(NS_LITERAL_STRING("error"), false, false);
   if (NS_FAILED(rv)) {
     NS_WARNING("Failed to init the error event!!!");
     return;
   }
 
@@ -1061,22 +1051,17 @@ EventSource::FailConnection()
 
   Close(); // it sets mReadyState to CLOSED
 
   rv = CheckInnerWindowCorrectness();
   if (NS_FAILED(rv)) {
     return;
   }
 
-  nsCOMPtr<nsIDOMEvent> event;
-  rv = NS_NewDOMEvent(getter_AddRefs(event), this, nullptr, nullptr);
-  if (NS_FAILED(rv)) {
-    NS_WARNING("Failed to create the error event!!!");
-    return;
-  }
+  nsRefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);
 
   // it doesn't bubble, and it isn't cancelable
   rv = event->InitEvent(NS_LITERAL_STRING("error"), false, false);
   if (NS_FAILED(rv)) {
     NS_WARNING("Failed to init the error event!!!");
     return;
   }
 
@@ -1229,37 +1214,30 @@ EventSource::DispatchAllMessageEvents()
       NS_ENSURE_TRUE_VOID(jsString);
 
       jsData.setString(jsString);
     }
 
     // create an event that uses the MessageEvent interface,
     // which does not bubble, is not cancelable, and has no default action
 
-    nsCOMPtr<nsIDOMEvent> event;
-    rv = NS_NewDOMMessageEvent(getter_AddRefs(event), this, nullptr, nullptr);
-    if (NS_FAILED(rv)) {
-      NS_WARNING("Failed to create the message event!!!");
-      return;
-    }
+    nsRefPtr<MessageEvent> event =
+      NS_NewDOMMessageEvent(this, nullptr, nullptr);
 
-    nsCOMPtr<nsIDOMMessageEvent> messageEvent = do_QueryInterface(event);
-    rv = messageEvent->InitMessageEvent(message->mEventName,
-                                        false, false,
-                                        jsData,
-                                        mOrigin,
-                                        message->mLastEventID, nullptr);
+    rv = event->InitMessageEvent(message->mEventName, false, false, jsData,
+                                 mOrigin, message->mLastEventID, nullptr);
     if (NS_FAILED(rv)) {
       NS_WARNING("Failed to init the message event!!!");
       return;
     }
 
-    messageEvent->SetTrusted(true);
+    event->SetTrusted(true);
 
-    rv = DispatchDOMEvent(nullptr, event, nullptr, nullptr);
+    rv = DispatchDOMEvent(nullptr, static_cast<Event*>(event), nullptr,
+                          nullptr);
     if (NS_FAILED(rv)) {
       NS_WARNING("Failed to dispatch the message event!!!");
       return;
     }
 
     mLastEventID.Assign(message->mLastEventID);
   }
 }

--- a/dom/base/WebSocket.cpp
+++ b/dom/base/WebSocket.cpp
@@ -8,16 +8,17 @@
 #include "mozilla/dom/WebSocketBinding.h"
 #include "mozilla/net/WebSocketChannel.h"
 
 #include "jsapi.h"
 #include "jsfriendapi.h"
 #include "mozilla/DOMEventTargetHelper.h"
 #include "mozilla/net/WebSocketChannel.h"
 #include "mozilla/dom/File.h"
+#include "mozilla/dom/MessageEvent.h"
 #include "mozilla/dom/nsCSPContext.h"
 #include "mozilla/dom/nsCSPUtils.h"
 #include "mozilla/dom/ScriptSettings.h"
 #include "mozilla/dom/WorkerPrivate.h"
 #include "mozilla/dom/WorkerRunnable.h"
 #include "mozilla/dom/WorkerScope.h"
 #include "nsIScriptGlobalObject.h"
 #include "nsIDOMWindow.h"
@@ -25,17 +26,16 @@
 #include "nsXPCOM.h"
 #include "nsIXPConnect.h"
 #include "nsContentUtils.h"
 #include "nsError.h"
 #include "nsIScriptObjectPrincipal.h"
 #include "nsIURL.h"
 #include "nsIUnicodeEncoder.h"
 #include "nsThreadUtils.h"
-#include "nsIDOMMessageEvent.h"
 #include "nsIPromptFactory.h"
 #include "nsIWindowWatcher.h"
 #include "nsIPrompt.h"
 #include "nsIStringBundle.h"
 #include "nsIConsoleService.h"
 #include "mozilla/dom/CloseEvent.h"
 #include "nsICryptoHash.h"
 #include "nsJSUtils.h"
@@ -1732,19 +1732,17 @@ WebSocket::CreateAndDispatchSimpleEvent(
   MOZ_ASSERT(mImpl);
   AssertIsOnTargetThread();
 
   nsresult rv = CheckInnerWindowCorrectness();
   if (NS_FAILED(rv)) {
     return NS_OK;
   }
 
-  nsCOMPtr<nsIDOMEvent> event;
-  rv = NS_NewDOMEvent(getter_AddRefs(event), this, nullptr, nullptr);
-  NS_ENSURE_SUCCESS(rv, rv);
+  nsRefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);
 
   // it doesn't bubble, and it isn't cancelable
   rv = event->InitEvent(aName, false, false);
   NS_ENSURE_SUCCESS(rv, rv);
 
   event->SetTrusted(true);
 
   return DispatchDOMEvent(nullptr, event, nullptr, nullptr);
@@ -1812,31 +1810,27 @@ WebSocket::CreateAndDispatchMessageEvent
     NS_ENSURE_TRUE(jsString, NS_ERROR_FAILURE);
 
     jsData.setString(jsString);
   }
 
   // create an event that uses the MessageEvent interface,
   // which does not bubble, is not cancelable, and has no default action
 
-  nsCOMPtr<nsIDOMEvent> event;
-  rv = NS_NewDOMMessageEvent(getter_AddRefs(event), this, nullptr, nullptr);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  nsCOMPtr<nsIDOMMessageEvent> messageEvent = do_QueryInterface(event);
-  rv = messageEvent->InitMessageEvent(NS_LITERAL_STRING("message"),
-                                      false, false,
-                                      jsData,
-                                      mImpl->mUTF16Origin,
-                                      EmptyString(), nullptr);
+  nsRefPtr<MessageEvent> event = NS_NewDOMMessageEvent(this, nullptr, nullptr);
+
+  rv = event->InitMessageEvent(NS_LITERAL_STRING("message"), false, false,
+                               jsData, mImpl->mUTF16Origin, EmptyString(),
+                               nullptr);
   NS_ENSURE_SUCCESS(rv, rv);
 
   event->SetTrusted(true);
 
-  return DispatchDOMEvent(nullptr, event, nullptr, nullptr);
+  return DispatchDOMEvent(nullptr, static_cast<Event*>(event), nullptr,
+                          nullptr);
 }
 
 nsresult
 WebSocket::CreateAndDispatchCloseEvent(bool aWasClean,
                                        uint16_t aCode,
                                        const nsAString &aReason)
 {
   MOZ_ASSERT(mImpl);

--- a/dom/base/nsDOMDataChannel.cpp
+++ b/dom/base/nsDOMDataChannel.cpp
@@ -12,19 +12,19 @@
 extern PRLogModuleInfo* GetDataChannelLog();
 #undef LOG
 #define LOG(args) MOZ_LOG(GetDataChannelLog(), mozilla::LogLevel::Debug, args)
 
 
 #include "nsDOMDataChannelDeclarations.h"
 #include "nsDOMDataChannel.h"
 #include "nsIDOMDataChannel.h"
-#include "nsIDOMMessageEvent.h"
 #include "mozilla/DOMEventTargetHelper.h"
 #include "mozilla/dom/File.h"
+#include "mozilla/dom/MessageEvent.h"
 #include "mozilla/dom/ScriptSettings.h"
 
 #include "nsError.h"
 #include "nsAutoPtr.h"
 #include "nsContentUtils.h"
 #include "nsCycleCollectionParticipant.h"
 #include "nsIScriptObjectPrincipal.h"
 
@@ -396,30 +396,25 @@ nsDOMDataChannel::DoOnMessageAvailable(c
   } else {
     NS_ConvertUTF8toUTF16 utf16data(aData);
     JSString* jsString = JS_NewUCStringCopyN(cx, utf16data.get(), utf16data.Length());
     NS_ENSURE_TRUE(jsString, NS_ERROR_FAILURE);
 
     jsData.setString(jsString);
   }
 
-  nsCOMPtr<nsIDOMEvent> event;
-  rv = NS_NewDOMMessageEvent(getter_AddRefs(event), this, nullptr, nullptr);
-  NS_ENSURE_SUCCESS(rv,rv);
+  nsRefPtr<MessageEvent> event = NS_NewDOMMessageEvent(this, nullptr, nullptr);
 
-  nsCOMPtr<nsIDOMMessageEvent> messageEvent = do_QueryInterface(event);
-  rv = messageEvent->InitMessageEvent(NS_LITERAL_STRING("message"),
-                                      false, false,
-                                      jsData, mOrigin, EmptyString(),
-                                      nullptr);
+  rv = event->InitMessageEvent(NS_LITERAL_STRING("message"), false, false,
+                               jsData, mOrigin, EmptyString(), nullptr);
   NS_ENSURE_SUCCESS(rv,rv);
   event->SetTrusted(true);
 
   LOG(("%p(%p): %s - Dispatching\n",this,(void*)mDataChannel,__FUNCTION__));
-  rv = DispatchDOMEvent(nullptr, event, nullptr, nullptr);
+  rv = DispatchDOMEvent(nullptr, static_cast<Event*>(event), nullptr, nullptr);
   if (NS_FAILED(rv)) {
     NS_WARNING("Failed to dispatch the message event!!!");
   }
   return rv;
 }
 
 nsresult
 nsDOMDataChannel::OnMessageAvailable(nsISupports* aContext,
@@ -442,19 +437,17 @@ nsDOMDataChannel::OnSimpleEvent(nsISuppo
 {
   MOZ_ASSERT(NS_IsMainThread());
 
   nsresult rv = CheckInnerWindowCorrectness();
   if (NS_FAILED(rv)) {
     return NS_OK;
   }
 
-  nsCOMPtr<nsIDOMEvent> event;
-  rv = NS_NewDOMEvent(getter_AddRefs(event), this, nullptr, nullptr);
-  NS_ENSURE_SUCCESS(rv,rv);
+  nsRefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);
 
   rv = event->InitEvent(aName, false, false);
   NS_ENSURE_SUCCESS(rv,rv);
 
   event->SetTrusted(true);
 
   return DispatchDOMEvent(nullptr, event, nullptr, nullptr);
 }

--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -8127,27 +8127,27 @@ nsIDocument::CreateEvent(const nsAString
   nsPresContext *presContext = nullptr;
 
   if (shell) {
     // Retrieve the context
     presContext = shell->GetPresContext();
   }
 
   // Create event even without presContext.
-  nsCOMPtr<nsIDOMEvent> ev;
-  rv = EventDispatcher::CreateEvent(const_cast<nsIDocument*>(this),
-                                    presContext, nullptr, aEventType,
-                                    getter_AddRefs(ev));
+  nsRefPtr<Event> ev =
+    EventDispatcher::CreateEvent(const_cast<nsIDocument*>(this), presContext,
+                                 nullptr, aEventType);
   if (!ev) {
+    rv.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
     return nullptr;
   }
   WidgetEvent* e = ev->GetInternalNSEvent();
   e->mFlags.mBubbles = false;
   e->mFlags.mCancelable = false;
-  return dont_AddRef(ev.forget().take()->InternalDOMEvent());
+  return ev.forget();
 }
 
 void
 nsDocument::FlushPendingNotifications(mozFlushType aType)
 {
   nsDocumentOnStack dos(this);
 
   // We need to flush the sink for non-HTML documents (because the XML
@@ -9204,18 +9204,17 @@ NotifyPageHide(nsIDocument* aDocument, v
   aDocument->OnPageHide(*aPersistedPtr, nullptr);
   return true;
 }
 
 static void
 DispatchCustomEventWithFlush(nsINode* aTarget, const nsAString& aEventType,
                              bool aBubbles, bool aOnlyChromeDispatch)
 {
-  nsCOMPtr<nsIDOMEvent> event;
-  NS_NewDOMEvent(getter_AddRefs(event), aTarget, nullptr, nullptr);
+  nsRefPtr<Event> event = NS_NewDOMEvent(aTarget, nullptr, nullptr);
   nsresult rv = event->InitEvent(aEventType, aBubbles, false);
   if (NS_FAILED(rv)) {
     return;
   }
   event->SetTrusted(true);
   if (aOnlyChromeDispatch) {
     event->GetInternalNSEvent()->mFlags.mOnlyChromeDispatch = true;
   }

--- a/dom/base/nsGlobalWindow.cpp
+++ b/dom/base/nsGlobalWindow.cpp
@@ -9096,18 +9096,17 @@ nsGlobalWindow::LeaveModalState()
   }
 
   // Remember the time of the last dialog quit.
   nsGlobalWindow *inner = topWin->GetCurrentInnerWindowInternal();
   if (inner)
     inner->mLastDialogQuitTime = TimeStamp::Now();
 
   if (topWin->mModalStateDepth == 0) {
-    nsCOMPtr<nsIDOMEvent> event;
-    NS_NewDOMEvent(getter_AddRefs(event), topWin, nullptr, nullptr);
+    nsRefPtr<Event> event = NS_NewDOMEvent(topWin, nullptr, nullptr);
     event->InitEvent(NS_LITERAL_STRING("endmodalstate"), true, false);
     event->SetTrusted(true);
     event->GetInternalNSEvent()->mFlags.mOnlyChromeDispatch = true;
     bool dummy;
     topWin->DispatchEvent(event, &dummy);
   }
 }
 
@@ -11885,18 +11884,17 @@ nsGlobalWindow::Observe(nsISupports* aSu
 #ifdef MOZ_B2G
   if (!nsCRT::strcmp(aTopic, NS_NETWORK_ACTIVITY_BLIP_UPLOAD_TOPIC) ||
       !nsCRT::strcmp(aTopic, NS_NETWORK_ACTIVITY_BLIP_DOWNLOAD_TOPIC)) {
     MOZ_ASSERT(IsInnerWindow());
     if (!IsCurrentInnerWindow()) {
       return NS_OK;
     }
 
-    nsCOMPtr<nsIDOMEvent> event;
-    NS_NewDOMEvent(getter_AddRefs(event), this, nullptr, nullptr);
+    nsRefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);
     nsresult rv = event->InitEvent(
       !nsCRT::strcmp(aTopic, NS_NETWORK_ACTIVITY_BLIP_UPLOAD_TOPIC)
         ? NETWORK_UPLOAD_EVENT_NAME
         : NETWORK_DOWNLOAD_EVENT_NAME,
       false, false);
     NS_ENSURE_SUCCESS(rv, rv);
 
     event->SetTrusted(true);
@@ -11922,18 +11920,17 @@ nsGlobalWindow::Observe(nsISupports* aSu
       NavigatorBinding::ClearCachedLanguagesValue(mNavigator);
     }
 
     // The event has to be dispatched only to the current inner window.
     if (!IsCurrentInnerWindow()) {
       return NS_OK;
     }
 
-    nsCOMPtr<nsIDOMEvent> event;
-    NS_NewDOMEvent(getter_AddRefs(event), this, nullptr, nullptr);
+    nsRefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);
     nsresult rv = event->InitEvent(NS_LITERAL_STRING("languagechange"), false, false);
     NS_ENSURE_SUCCESS(rv, rv);
 
     event->SetTrusted(true);
 
     bool dummy;
     return DispatchEvent(event, &dummy);
   }

--- a/dom/base/nsPerformance.cpp
+++ b/dom/base/nsPerformance.cpp
@@ -473,26 +473,25 @@ nsPerformance::Timing()
         mDOMTiming->GetNavigationStart());
   }
   return mTiming;
 }
 
 void
 nsPerformance::DispatchBufferFullEvent()
 {
-  nsCOMPtr<nsIDOMEvent> event;
-  nsresult rv = NS_NewDOMEvent(getter_AddRefs(event), this, nullptr, nullptr);
-  if (NS_SUCCEEDED(rv)) {
-    // it bubbles, and it isn't cancelable
-    rv = event->InitEvent(NS_LITERAL_STRING("resourcetimingbufferfull"), true, false);
-    if (NS_SUCCEEDED(rv)) {
-      event->SetTrusted(true);
-      DispatchDOMEvent(nullptr, event, nullptr, nullptr);
-    }
+  nsRefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);
+  // it bubbles, and it isn't cancelable
+  nsresult rv = event->InitEvent(NS_LITERAL_STRING("resourcetimingbufferfull"),
+                                 true, false);
+  if (NS_FAILED(rv)) {
+    return;
   }
+  event->SetTrusted(true);
+  DispatchDOMEvent(nullptr, event, nullptr, nullptr);
 }
 
 nsPerformanceNavigation*
 nsPerformance::Navigation()
 {
   if (!mNavigation) {
     mNavigation = new nsPerformanceNavigation(this);
   }

--- a/dom/base/nsXMLHttpRequest.cpp
+++ b/dom/base/nsXMLHttpRequest.cpp
@@ -1462,22 +1462,18 @@ nsXMLHttpRequest::GetLoadGroup() const
   }
 
   return nullptr;
 }
 
 nsresult
 nsXMLHttpRequest::CreateReadystatechangeEvent(nsIDOMEvent** aDOMEvent)
 {
-  nsresult rv = EventDispatcher::CreateEvent(this, nullptr, nullptr,
-                                             NS_LITERAL_STRING("Events"),
-                                             aDOMEvent);
-  if (NS_FAILED(rv)) {
-    return rv;
-  }
+  nsRefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);
+  event.forget(aDOMEvent);
 
   (*aDOMEvent)->InitEvent(NS_LITERAL_STRING(READYSTATE_STR),
                           false, false);
 
   // We assume anyone who managed to call CreateReadystatechangeEvent is trusted
   (*aDOMEvent)->SetTrusted(true);
 
   return NS_OK;

--- a/dom/bluetooth/bluetooth1/BluetoothAdapter.cpp
+++ b/dom/bluetooth/bluetooth1/BluetoothAdapter.cpp
@@ -11,16 +11,17 @@
 #include "nsThreadUtils.h"
 
 #include "mozilla/dom/bluetooth/BluetoothTypes.h"
 #include "mozilla/dom/BluetoothAdapterBinding.h"
 #include "mozilla/dom/BluetoothDeviceEvent.h"
 #include "mozilla/dom/BluetoothDiscoveryStateChangedEvent.h"
 #include "mozilla/dom/BluetoothStatusChangedEvent.h"
 #include "mozilla/dom/ContentChild.h"
+#include "mozilla/dom/Event.h"
 #include "mozilla/dom/File.h"
 #include "mozilla/dom/ScriptSettings.h"
 #include "mozilla/LazyIdleThread.h"
 
 #include "BluetoothAdapter.h"
 #include "BluetoothDevice.h"
 #include "BluetoothReplyRunnable.h"
 #include "BluetoothService.h"
@@ -356,21 +357,19 @@ BluetoothAdapter::Notify(const Bluetooth
     init.mBubbles = false;
     init.mCancelable = false;
     init.mAddress = address;
     init.mStatus = status;
     nsRefPtr<BluetoothStatusChangedEvent> event =
       BluetoothStatusChangedEvent::Constructor(this, aData.name(), init);
     DispatchTrustedEvent(event);
   } else if (aData.name().EqualsLiteral(REQUEST_MEDIA_PLAYSTATUS_ID)) {
-    nsCOMPtr<nsIDOMEvent> event;
-    nsresult rv = NS_NewDOMEvent(getter_AddRefs(event), this, nullptr, nullptr);
-    NS_ENSURE_SUCCESS_VOID(rv);
+    nsRefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);
 
-    rv = event->InitEvent(aData.name(), false, false);
+    nsresult rv = event->InitEvent(aData.name(), false, false);
     NS_ENSURE_SUCCESS_VOID(rv);
 
     DispatchTrustedEvent(event);
   } else {
 #ifdef DEBUG
     nsCString warningMsg;
     warningMsg.AssignLiteral("Not handling adapter signal: ");
     warningMsg.Append(NS_ConvertUTF16toUTF8(aData.name()));

--- a/dom/bluetooth/bluetooth2/BluetoothAdapter.cpp
+++ b/dom/bluetooth/bluetooth2/BluetoothAdapter.cpp
@@ -11,16 +11,17 @@
 #include "nsIDocument.h"
 #include "nsIPrincipal.h"
 #include "nsTArrayHelpers.h"
 
 #include "mozilla/dom/BluetoothAdapter2Binding.h"
 #include "mozilla/dom/BluetoothAttributeEvent.h"
 #include "mozilla/dom/BluetoothStatusChangedEvent.h"
 #include "mozilla/dom/ContentChild.h"
+#include "mozilla/dom/Event.h"
 #include "mozilla/dom/File.h"
 
 #include "mozilla/dom/bluetooth/BluetoothAdapter.h"
 #include "mozilla/dom/bluetooth/BluetoothClassOfDevice.h"
 #include "mozilla/dom/bluetooth/BluetoothDevice.h"
 #include "mozilla/dom/bluetooth/BluetoothDiscoveryHandle.h"
 #include "mozilla/dom/bluetooth/BluetoothGattServer.h"
 #include "mozilla/dom/bluetooth/BluetoothPairingListener.h"
@@ -1191,21 +1192,19 @@ BluetoothAdapter::DispatchDeviceEvent(co
   nsRefPtr<BluetoothDeviceEvent> event =
     BluetoothDeviceEvent::Constructor(this, aType, aInit);
   DispatchTrustedEvent(event);
 }
 
 void
 BluetoothAdapter::DispatchEmptyEvent(const nsAString& aType)
 {
-  nsCOMPtr<nsIDOMEvent> event;
-  nsresult rv = NS_NewDOMEvent(getter_AddRefs(event), this, nullptr, nullptr);
-  NS_ENSURE_SUCCESS_VOID(rv);
+  nsRefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);
 
-  rv = event->InitEvent(aType, false, false);
+  nsresult rv = event->InitEvent(aType, false, false);
   NS_ENSURE_SUCCESS_VOID(rv);
 
   DispatchTrustedEvent(event);
 }
 
 already_AddRefed<DOMRequest>
 BluetoothAdapter::Connect(BluetoothDevice& aDevice,
                           const Optional<short unsigned int>& aServiceUuid,

--- a/dom/bluetooth/bluetooth2/BluetoothGatt.cpp
+++ b/dom/bluetooth/bluetooth2/BluetoothGatt.cpp
@@ -7,16 +7,17 @@
 #include "BluetoothReplyRunnable.h"
 #include "BluetoothService.h"
 #include "BluetoothUtils.h"
 #include "mozilla/dom/bluetooth/BluetoothCommon.h"
 #include "mozilla/dom/bluetooth/BluetoothGatt.h"
 #include "mozilla/dom/bluetooth/BluetoothTypes.h"
 #include "mozilla/dom/BluetoothGattBinding.h"
 #include "mozilla/dom/BluetoothGattCharacteristicEvent.h"
+#include "mozilla/dom/Event.h"
 #include "mozilla/dom/Promise.h"
 #include "nsServiceManagerUtils.h"
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
 USING_BLUETOOTH_NAMESPACE
 
@@ -235,23 +236,22 @@ BluetoothGatt::DiscoverServices(ErrorRes
 
 void
 BluetoothGatt::UpdateConnectionState(BluetoothConnectionState aState)
 {
   BT_LOGR("GATT connection state changes to: %d", int(aState));
   mConnectionState = aState;
 
   // Dispatch connectionstatechanged event to application
-  nsCOMPtr<nsIDOMEvent> event;
-  nsresult rv = NS_NewDOMEvent(getter_AddRefs(event), this, nullptr, nullptr);
-  NS_ENSURE_SUCCESS_VOID(rv);
+  nsRefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);
 
-  rv = event->InitEvent(NS_LITERAL_STRING(GATT_CONNECTION_STATE_CHANGED_ID),
-                        false,
-                        false);
+  nsresult rv =
+    event->InitEvent(NS_LITERAL_STRING(GATT_CONNECTION_STATE_CHANGED_ID),
+                     false,
+                     false);
   NS_ENSURE_SUCCESS_VOID(rv);
 
   DispatchTrustedEvent(event);
 }
 
 void
 BluetoothGatt::HandleServicesDiscovered(const BluetoothValue& aValue)
 {

--- a/dom/browser-element/BrowserElementParent.cpp
+++ b/dom/browser-element/BrowserElementParent.cpp
@@ -97,41 +97,36 @@ DispatchCustomDOMEvent(Element* aFrameEl
 {
   NS_ENSURE_TRUE(aFrameElement, false);
   nsIPresShell *shell = aFrameElement->OwnerDoc()->GetShell();
   nsRefPtr<nsPresContext> presContext;
   if (shell) {
     presContext = shell->GetPresContext();
   }
 
-  nsCOMPtr<nsIDOMEvent> domEvent;
-  EventDispatcher::CreateEvent(aFrameElement, presContext, nullptr,
-                               NS_LITERAL_STRING("customevent"),
-                               getter_AddRefs(domEvent));
-  NS_ENSURE_TRUE(domEvent, false);
+  nsRefPtr<CustomEvent> event =
+    NS_NewDOMCustomEvent(aFrameElement, presContext, nullptr);
 
-  nsCOMPtr<nsIDOMCustomEvent> customEvent = do_QueryInterface(domEvent);
-  NS_ENSURE_TRUE(customEvent, false);
   ErrorResult res;
-  CustomEvent* event = static_cast<CustomEvent*>(customEvent.get());
   event->InitCustomEvent(cx,
                          aEventName,
                          /* bubbles = */ true,
                          /* cancelable = */ true,
                          aDetailValue,
                          res);
   if (res.Failed()) {
     return false;
   }
-  customEvent->SetTrusted(true);
+  event->SetTrusted(true);
   // Dispatch the event.
   *aStatus = nsEventStatus_eConsumeNoDefault;
   nsresult rv =
     EventDispatcher::DispatchDOMEvent(aFrameElement, nullptr,
-                                      domEvent, presContext, aStatus);
+                                      static_cast<Event*>(event),
+                                      presContext, aStatus);
   return NS_SUCCEEDED(rv);
 }
 
 } // namespace
 
 namespace mozilla {
 
 /**

--- a/dom/events/AnimationEvent.cpp
+++ b/dom/events/AnimationEvent.cpp
@@ -83,19 +83,17 @@ AnimationEvent::GetPseudoElement(nsAStri
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMAnimationEvent(nsIDOMEvent** aInstancePtrResult,
-                        EventTarget* aOwner,
+already_AddRefed<AnimationEvent>
+NS_NewDOMAnimationEvent(EventTarget* aOwner,
                         nsPresContext* aPresContext,
                         InternalAnimationEvent* aEvent)
 {
-  AnimationEvent* it = new AnimationEvent(aOwner, aPresContext, aEvent);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<AnimationEvent> it =
+    new AnimationEvent(aOwner, aPresContext, aEvent);
+  return it.forget();
 }

--- a/dom/events/AnimationEvent.h
+++ b/dom/events/AnimationEvent.h
@@ -47,9 +47,14 @@ public:
 
 protected:
   ~AnimationEvent() {}
 };
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::AnimationEvent>
+NS_NewDOMAnimationEvent(mozilla::dom::EventTarget* aOwner,
+                        nsPresContext* aPresContext,
+                        mozilla::InternalAnimationEvent* aEvent);
+
 #endif // mozilla_dom_AnimationEvent_h_

--- a/dom/events/AsyncEventDispatcher.cpp
+++ b/dom/events/AsyncEventDispatcher.cpp
@@ -21,35 +21,36 @@ using namespace dom;
  ******************************************************************************/
 
 AsyncEventDispatcher::AsyncEventDispatcher(EventTarget* aTarget,
                                            WidgetEvent& aEvent)
   : mTarget(aTarget)
   , mOnlyChromeDispatch(false)
 {
   MOZ_ASSERT(mTarget);
-  EventDispatcher::CreateEvent(aTarget, nullptr, &aEvent, EmptyString(),
-                               getter_AddRefs(mEvent));
+  nsRefPtr<Event> event =
+    EventDispatcher::CreateEvent(aTarget, nullptr, &aEvent, EmptyString());
+  mEvent = do_QueryInterface(event);
   NS_ASSERTION(mEvent, "Should never fail to create an event");
   mEvent->DuplicatePrivateData();
   mEvent->SetTrusted(aEvent.mFlags.mIsTrusted);
 }
 
 NS_IMETHODIMP
 AsyncEventDispatcher::Run()
 {
-  nsCOMPtr<nsIDOMEvent> event = mEvent;
+  nsRefPtr<Event> event = mEvent ? mEvent->InternalDOMEvent() : nullptr;
   if (!event) {
-    NS_NewDOMEvent(getter_AddRefs(event), mTarget, nullptr, nullptr);
+    event = NS_NewDOMEvent(mTarget, nullptr, nullptr);
     nsresult rv = event->InitEvent(mEventType, mBubbles, false);
     NS_ENSURE_SUCCESS(rv, rv);
     event->SetTrusted(true);
   }
   if (mOnlyChromeDispatch) {
-    MOZ_ASSERT(event->InternalDOMEvent()->IsTrusted());
+    MOZ_ASSERT(event->IsTrusted());
     event->GetInternalNSEvent()->mFlags.mOnlyChromeDispatch = true;
   }
   bool dummy;
   mTarget->DispatchEvent(event, &dummy);
   return NS_OK;
 }
 
 nsresult

--- a/dom/events/BeforeAfterKeyboardEvent.cpp
+++ b/dom/events/BeforeAfterKeyboardEvent.cpp
@@ -73,21 +73,17 @@ BeforeAfterKeyboardEvent::GetEmbeddedCan
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMBeforeAfterKeyboardEvent(nsIDOMEvent** aInstancePtrResult,
-                                  EventTarget* aOwner,
+already_AddRefed<BeforeAfterKeyboardEvent>
+NS_NewDOMBeforeAfterKeyboardEvent(EventTarget* aOwner,
                                   nsPresContext* aPresContext,
                                   InternalBeforeAfterKeyboardEvent* aEvent)
 {
-  BeforeAfterKeyboardEvent* it =
+  nsRefPtr<BeforeAfterKeyboardEvent> it =
     new BeforeAfterKeyboardEvent(aOwner, aPresContext, aEvent);
-
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  return it.forget();
 }

--- a/dom/events/BeforeAfterKeyboardEvent.h
+++ b/dom/events/BeforeAfterKeyboardEvent.h
@@ -38,9 +38,14 @@ public:
   // This function returns a boolean value when event typs is either
   // "mozbrowserafterkeydown" or "mozbrowserafterkeyup".
   Nullable<bool> GetEmbeddedCancelled();
 };
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::BeforeAfterKeyboardEvent>
+NS_NewDOMBeforeAfterKeyboardEvent(mozilla::dom::EventTarget* aOwner,
+                                  nsPresContext* aPresContext,
+                                  mozilla::InternalBeforeAfterKeyboardEvent* aEvent);
+
 #endif // mozilla_dom_BeforeAfterKeyboardEvent_h_

--- a/dom/events/BeforeUnloadEvent.cpp
+++ b/dom/events/BeforeUnloadEvent.cpp
@@ -31,19 +31,17 @@ BeforeUnloadEvent::GetReturnValue(nsAStr
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMBeforeUnloadEvent(nsIDOMEvent** aInstancePtrResult,
-                           EventTarget* aOwner,
+already_AddRefed<BeforeUnloadEvent>
+NS_NewDOMBeforeUnloadEvent(EventTarget* aOwner,
                            nsPresContext* aPresContext,
                            WidgetEvent* aEvent) 
 {
-  BeforeUnloadEvent* it = new BeforeUnloadEvent(aOwner, aPresContext, aEvent);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<BeforeUnloadEvent> it =
+    new BeforeUnloadEvent(aOwner, aPresContext, aEvent);
+  return it.forget();
 }

--- a/dom/events/BeforeUnloadEvent.h
+++ b/dom/events/BeforeUnloadEvent.h
@@ -42,9 +42,14 @@ protected:
   ~BeforeUnloadEvent() {}
 
   nsString mText;
 };
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::BeforeUnloadEvent>
+NS_NewDOMBeforeUnloadEvent(mozilla::dom::EventTarget* aOwner,
+                           nsPresContext* aPresContext,
+                           mozilla::WidgetEvent* aEvent);
+
 #endif // mozilla_dom_BeforeUnloadEvent_h_

--- a/dom/events/ClipboardEvent.cpp
+++ b/dom/events/ClipboardEvent.cpp
@@ -118,19 +118,17 @@ ClipboardEvent::GetClipboardData()
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMClipboardEvent(nsIDOMEvent** aInstancePtrResult,
-                        EventTarget* aOwner,
+already_AddRefed<ClipboardEvent>
+NS_NewDOMClipboardEvent(EventTarget* aOwner,
                         nsPresContext* aPresContext,
                         InternalClipboardEvent* aEvent)
 {
-  ClipboardEvent* it = new ClipboardEvent(aOwner, aPresContext, aEvent);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<ClipboardEvent> it =
+    new ClipboardEvent(aOwner, aPresContext, aEvent);
+  return it.forget();
 }

--- a/dom/events/ClipboardEvent.h
+++ b/dom/events/ClipboardEvent.h
@@ -51,9 +51,14 @@ public:
 
 protected:
   ~ClipboardEvent() {}
 };
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::ClipboardEvent>
+NS_NewDOMClipboardEvent(mozilla::dom::EventTarget* aOwner,
+                        nsPresContext* aPresContext,
+                        mozilla::InternalClipboardEvent* aEvent);
+
 #endif // mozilla_dom_ClipboardEvent_h_

--- a/dom/events/CommandEvent.cpp
+++ b/dom/events/CommandEvent.cpp
@@ -59,19 +59,17 @@ CommandEvent::InitCommandEvent(const nsA
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMCommandEvent(nsIDOMEvent** aInstancePtrResult,
-                      EventTarget* aOwner,
+already_AddRefed<CommandEvent>
+NS_NewDOMCommandEvent(EventTarget* aOwner,
                       nsPresContext* aPresContext,
                       WidgetCommandEvent* aEvent)
 {
-  CommandEvent* it = new CommandEvent(aOwner, aPresContext, aEvent);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<CommandEvent> it =
+    new CommandEvent(aOwner, aPresContext, aEvent);
+  return it.forget();
 }

--- a/dom/events/CommandEvent.h
+++ b/dom/events/CommandEvent.h
@@ -46,9 +46,14 @@ public:
 
 protected:
   ~CommandEvent() {}
 };
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::CommandEvent>
+NS_NewDOMCommandEvent(mozilla::dom::EventTarget* aOwner,
+                      nsPresContext* aPresContext,
+                      mozilla::WidgetCommandEvent* aEvent);
+
 #endif // mozilla_dom_CommandEvent_h_

--- a/dom/events/CompositionEvent.cpp
+++ b/dom/events/CompositionEvent.cpp
@@ -75,17 +75,17 @@ CompositionEvent::InitCompositionEvent(c
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMCompositionEvent(nsIDOMEvent** aInstancePtrResult,
-                          EventTarget* aOwner,
+already_AddRefed<CompositionEvent>
+NS_NewDOMCompositionEvent(EventTarget* aOwner,
                           nsPresContext* aPresContext,
                           WidgetCompositionEvent* aEvent)
 {
-  CompositionEvent* event = new CompositionEvent(aOwner, aPresContext, aEvent);
-  return CallQueryInterface(event, aInstancePtrResult);
+  nsRefPtr<CompositionEvent> event =
+    new CompositionEvent(aOwner, aPresContext, aEvent);
+  return event.forget();
 }

--- a/dom/events/CompositionEvent.h
+++ b/dom/events/CompositionEvent.h
@@ -49,9 +49,14 @@ protected:
 
   nsString mData;
   nsString mLocale;
 };
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::CompositionEvent>
+NS_NewDOMCompositionEvent(mozilla::dom::EventTarget* aOwner,
+                          nsPresContext* aPresContext,
+                          mozilla::WidgetCompositionEvent* aEvent);
+
 #endif // mozilla_dom_CompositionEvent_h_

--- a/dom/events/CustomEvent.cpp
+++ b/dom/events/CustomEvent.cpp
@@ -106,19 +106,17 @@ CustomEvent::GetDetail(JSContext* aCx,
   if (!mDetail) {
     aRetval.setNull();
     return;
   }
 
   VariantToJsval(aCx, mDetail, aRetval);
 }
 
-nsresult
-NS_NewDOMCustomEvent(nsIDOMEvent** aInstancePtrResult,
-                     mozilla::dom::EventTarget* aOwner,
+already_AddRefed<CustomEvent>
+NS_NewDOMCustomEvent(EventTarget* aOwner,
                      nsPresContext* aPresContext,
                      mozilla::WidgetEvent* aEvent)
 {
-  CustomEvent* it = new CustomEvent(aOwner, aPresContext, aEvent);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<CustomEvent> it =
+    new CustomEvent(aOwner, aPresContext, aEvent);
+  return it.forget();
 }

--- a/dom/events/CustomEvent.h
+++ b/dom/events/CustomEvent.h
@@ -53,9 +53,14 @@ public:
                   bool aCancelable,
                   JS::Handle<JS::Value> aDetail,
                   ErrorResult& aRv);
 };
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::CustomEvent>
+NS_NewDOMCustomEvent(mozilla::dom::EventTarget* aOwner,
+                     nsPresContext* aPresContext,
+                     mozilla::WidgetEvent* aEvent);
+
 #endif // CustomEvent_h__

--- a/dom/events/DOMEventTargetHelper.cpp
+++ b/dom/events/DOMEventTargetHelper.cpp
@@ -257,18 +257,17 @@ DOMEventTargetHelper::DispatchEvent(nsID
 
   *aRetVal = (status != nsEventStatus_eConsumeNoDefault);
   return rv;
 }
 
 nsresult
 DOMEventTargetHelper::DispatchTrustedEvent(const nsAString& aEventName)
 {
-  nsCOMPtr<nsIDOMEvent> event;
-  NS_NewDOMEvent(getter_AddRefs(event), this, nullptr, nullptr);
+  nsRefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);
   nsresult rv = event->InitEvent(aEventName, false, false);
   NS_ENSURE_SUCCESS(rv, rv);
 
   return DispatchTrustedEvent(event);
 }
 
 nsresult
 DOMEventTargetHelper::DispatchTrustedEvent(nsIDOMEvent* event)

--- a/dom/events/DataContainerEvent.cpp
+++ b/dom/events/DataContainerEvent.cpp
@@ -82,20 +82,18 @@ DataContainerEvent::SetData(JSContext* a
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMDataContainerEvent(nsIDOMEvent** aInstancePtrResult,
-                            EventTarget* aOwner,
+already_AddRefed<DataContainerEvent>
+NS_NewDOMDataContainerEvent(EventTarget* aOwner,
                             nsPresContext* aPresContext,
                             WidgetEvent* aEvent)
 {
-  DataContainerEvent* it = new DataContainerEvent(aOwner, aPresContext, aEvent);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<DataContainerEvent> it =
+    new DataContainerEvent(aOwner, aPresContext, aEvent);
+  return it.forget();
 }
 

--- a/dom/events/DataContainerEvent.h
+++ b/dom/events/DataContainerEvent.h
@@ -52,9 +52,14 @@ protected:
 
 private:
   nsInterfaceHashtable<nsStringHashKey, nsIVariant> mData;
 };
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::DataContainerEvent>
+NS_NewDOMDataContainerEvent(mozilla::dom::EventTarget* aOwner,
+                            nsPresContext* aPresContext,
+                            mozilla::WidgetEvent* aEvent);
+
 #endif // mozilla_dom_DataContainerEvent_h_

--- a/dom/events/DeviceMotionEvent.cpp
+++ b/dom/events/DeviceMotionEvent.cpp
@@ -140,21 +140,17 @@ DeviceRotationRate::~DeviceRotationRate(
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMDeviceMotionEvent(nsIDOMEvent** aInstancePtrResult,
-                           EventTarget* aOwner,
+already_AddRefed<DeviceMotionEvent>
+NS_NewDOMDeviceMotionEvent(EventTarget* aOwner,
                            nsPresContext* aPresContext,
                            WidgetEvent* aEvent) 
 {
-  NS_ENSURE_ARG_POINTER(aInstancePtrResult);
-
-  DeviceMotionEvent* it = new DeviceMotionEvent(aOwner, aPresContext, aEvent);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<DeviceMotionEvent> it =
+    new DeviceMotionEvent(aOwner, aPresContext, aEvent);
+  return it.forget();
 }

--- a/dom/events/DeviceMotionEvent.h
+++ b/dom/events/DeviceMotionEvent.h
@@ -144,9 +144,14 @@ protected:
   nsRefPtr<DeviceAcceleration> mAccelerationIncludingGravity;
   nsRefPtr<DeviceRotationRate> mRotationRate;
   Nullable<double> mInterval;
 };
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::DeviceMotionEvent>
+NS_NewDOMDeviceMotionEvent(mozilla::dom::EventTarget* aOwner,
+                           nsPresContext* aPresContext,
+                           mozilla::WidgetEvent* aEvent);
+
 #endif // mozilla_dom_DeviceMotionEvent_h_

--- a/dom/events/DragEvent.cpp
+++ b/dom/events/DragEvent.cpp
@@ -154,17 +154,17 @@ DragEvent::Constructor(const GlobalObjec
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMDragEvent(nsIDOMEvent** aInstancePtrResult,
-                   EventTarget* aOwner,
+already_AddRefed<DragEvent>
+NS_NewDOMDragEvent(EventTarget* aOwner,
                    nsPresContext* aPresContext,
                    WidgetDragEvent* aEvent) 
 {
-  DragEvent* event = new DragEvent(aOwner, aPresContext, aEvent);
-  return CallQueryInterface(event, aInstancePtrResult);
+  nsRefPtr<DragEvent> event =
+    new DragEvent(aOwner, aPresContext, aEvent);
+  return event.forget();
 }

--- a/dom/events/DragEvent.h
+++ b/dom/events/DragEvent.h
@@ -56,9 +56,14 @@ public:
 
 protected:
   ~DragEvent() {}
 };
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::DragEvent>
+NS_NewDOMDragEvent(mozilla::dom::EventTarget* aOwner,
+                   nsPresContext* aPresContext,
+                   mozilla::WidgetDragEvent* aEvent);
+
 #endif // mozilla_dom_DragEvent_h_

--- a/dom/events/Event.cpp
+++ b/dom/events/Event.cpp
@@ -1252,19 +1252,16 @@ Event::GetShadowRelatedTarget(nsIContent
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMEvent(nsIDOMEvent** aInstancePtrResult,
-               EventTarget* aOwner,
+already_AddRefed<Event>
+NS_NewDOMEvent(EventTarget* aOwner,
                nsPresContext* aPresContext,
                WidgetEvent* aEvent) 
 {
-  Event* it = new Event(aOwner, aPresContext, aEvent);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<Event> it = new Event(aOwner, aPresContext, aEvent);
+  return it.forget();
 }

--- a/dom/events/Event.h
+++ b/dom/events/Event.h
@@ -335,9 +335,14 @@ ToSupports(mozilla::dom::Event* e)
 }
 
 inline nsISupports*
 ToCanonicalSupports(mozilla::dom::Event* e)
 {
   return static_cast<nsIDOMEvent*>(e);
 }
 
+already_AddRefed<mozilla::dom::Event>
+NS_NewDOMEvent(mozilla::dom::EventTarget* aOwner,
+               nsPresContext* aPresContext,
+               mozilla::WidgetEvent* aEvent);
+
 #endif // mozilla_dom_Event_h_

--- a/dom/events/EventDispatcher.cpp
+++ b/dom/events/EventDispatcher.cpp
@@ -10,23 +10,38 @@
 #include <new>
 #include "nsIContent.h"
 #include "nsIDocument.h"
 #include "nsINode.h"
 #include "nsPIDOMWindow.h"
 #include "GeckoProfiler.h"
 #include "mozilla/ContentEvents.h"
 #include "mozilla/dom/CloseEvent.h"
+#include "mozilla/dom/CustomEvent.h"
 #include "mozilla/dom/DeviceOrientationEvent.h"
 #include "mozilla/dom/EventTarget.h"
+#include "mozilla/dom/FocusEvent.h"
 #include "mozilla/dom/HashChangeEvent.h"
+#include "mozilla/dom/InputEvent.h"
+#include "mozilla/dom/MessageEvent.h"
+#include "mozilla/dom/MouseScrollEvent.h"
+#include "mozilla/dom/MutationEvent.h"
+#include "mozilla/dom/NotifyPaintEvent.h"
 #include "mozilla/dom/PageTransitionEvent.h"
+#include "mozilla/dom/PointerEvent.h"
 #include "mozilla/dom/PopStateEvent.h"
+#include "mozilla/dom/ScrollAreaEvent.h"
+#include "mozilla/dom/SimpleGestureEvent.h"
 #include "mozilla/dom/StorageEvent.h"
+#include "mozilla/dom/SVGZoomEvent.h"
+#include "mozilla/dom/TimeEvent.h"
 #include "mozilla/dom/TouchEvent.h"
+#include "mozilla/dom/TransitionEvent.h"
+#include "mozilla/dom/WheelEvent.h"
+#include "mozilla/dom/XULCommandEvent.h"
 #include "mozilla/EventDispatcher.h"
 #include "mozilla/EventListenerManager.h"
 #include "mozilla/InternalMutationEvent.h"
 #include "mozilla/ipc/MessageChannel.h"
 #include "mozilla/MiscEvents.h"
 #include "mozilla/MouseEvents.h"
 #include "mozilla/TextEvents.h"
 #include "mozilla/TouchEvents.h"
@@ -700,198 +715,177 @@ EventDispatcher::DispatchDOMEvent(nsISup
                                      aDOMEvent, aEventStatus);
   } else if (aEvent) {
     return EventDispatcher::Dispatch(aTarget, aPresContext, aEvent,
                                      aDOMEvent, aEventStatus);
   }
   return NS_ERROR_ILLEGAL_VALUE;
 }
 
-/* static */ nsresult
+/* static */ already_AddRefed<dom::Event>
 EventDispatcher::CreateEvent(EventTarget* aOwner,
                              nsPresContext* aPresContext,
                              WidgetEvent* aEvent,
-                             const nsAString& aEventType,
-                             nsIDOMEvent** aDOMEvent)
+                             const nsAString& aEventType)
 {
-  *aDOMEvent = nullptr;
-
   if (aEvent) {
     switch(aEvent->mClass) {
     case eMutationEventClass:
-      return NS_NewDOMMutationEvent(aDOMEvent, aOwner, aPresContext,
+      return NS_NewDOMMutationEvent(aOwner, aPresContext,
                                     aEvent->AsMutationEvent());
     case eGUIEventClass:
     case eScrollPortEventClass:
     case eUIEventClass:
-      return NS_NewDOMUIEvent(aDOMEvent, aOwner, aPresContext,
-                              aEvent->AsGUIEvent());
+      return NS_NewDOMUIEvent(aOwner, aPresContext, aEvent->AsGUIEvent());
     case eScrollAreaEventClass:
-      return NS_NewDOMScrollAreaEvent(aDOMEvent, aOwner, aPresContext,
+      return NS_NewDOMScrollAreaEvent(aOwner, aPresContext,
                                       aEvent->AsScrollAreaEvent());
     case eKeyboardEventClass:
-      return NS_NewDOMKeyboardEvent(aDOMEvent, aOwner, aPresContext,
+      return NS_NewDOMKeyboardEvent(aOwner, aPresContext,
                                     aEvent->AsKeyboardEvent());
     case eBeforeAfterKeyboardEventClass:
-      return NS_NewDOMBeforeAfterKeyboardEvent(aDOMEvent, aOwner, aPresContext,
+      return NS_NewDOMBeforeAfterKeyboardEvent(aOwner, aPresContext,
                                                aEvent->AsBeforeAfterKeyboardEvent());
     case eCompositionEventClass:
-      return NS_NewDOMCompositionEvent(aDOMEvent, aOwner, aPresContext,
+      return NS_NewDOMCompositionEvent(aOwner, aPresContext,
                                        aEvent->AsCompositionEvent());
     case eMouseEventClass:
-      return NS_NewDOMMouseEvent(aDOMEvent, aOwner, aPresContext,
-                                 aEvent->AsMouseEvent());
+      return NS_NewDOMMouseEvent(aOwner, aPresContext, aEvent->AsMouseEvent());
     case eFocusEventClass:
-      return NS_NewDOMFocusEvent(aDOMEvent, aOwner, aPresContext,
-                                 aEvent->AsFocusEvent());
+      return NS_NewDOMFocusEvent(aOwner, aPresContext, aEvent->AsFocusEvent());
     case eMouseScrollEventClass:
-      return NS_NewDOMMouseScrollEvent(aDOMEvent, aOwner, aPresContext,
+      return NS_NewDOMMouseScrollEvent(aOwner, aPresContext,
                                        aEvent->AsMouseScrollEvent());
     case eWheelEventClass:
-      return NS_NewDOMWheelEvent(aDOMEvent, aOwner, aPresContext,
-                                 aEvent->AsWheelEvent());
+      return NS_NewDOMWheelEvent(aOwner, aPresContext, aEvent->AsWheelEvent());
     case eEditorInputEventClass:
-      return NS_NewDOMInputEvent(aDOMEvent, aOwner, aPresContext,
+      return NS_NewDOMInputEvent(aOwner, aPresContext,
                                  aEvent->AsEditorInputEvent());
     case eDragEventClass:
-      return NS_NewDOMDragEvent(aDOMEvent, aOwner, aPresContext,
-                                aEvent->AsDragEvent());
+      return NS_NewDOMDragEvent(aOwner, aPresContext, aEvent->AsDragEvent());
     case eClipboardEventClass:
-      return NS_NewDOMClipboardEvent(aDOMEvent, aOwner, aPresContext,
+      return NS_NewDOMClipboardEvent(aOwner, aPresContext,
                                      aEvent->AsClipboardEvent());
     case eSVGZoomEventClass:
-      return NS_NewDOMSVGZoomEvent(aDOMEvent, aOwner, aPresContext,
+      return NS_NewDOMSVGZoomEvent(aOwner, aPresContext,
                                    aEvent->AsSVGZoomEvent());
     case eSMILTimeEventClass:
-      return NS_NewDOMTimeEvent(aDOMEvent, aOwner, aPresContext,
+      return NS_NewDOMTimeEvent(aOwner, aPresContext,
                                 aEvent->AsSMILTimeEvent());
     case eCommandEventClass:
-      return NS_NewDOMCommandEvent(aDOMEvent, aOwner, aPresContext,
+      return NS_NewDOMCommandEvent(aOwner, aPresContext,
                                    aEvent->AsCommandEvent());
     case eSimpleGestureEventClass:
-      return NS_NewDOMSimpleGestureEvent(aDOMEvent, aOwner, aPresContext,
+      return NS_NewDOMSimpleGestureEvent(aOwner, aPresContext,
                                          aEvent->AsSimpleGestureEvent());
     case ePointerEventClass:
-      return NS_NewDOMPointerEvent(aDOMEvent, aOwner, aPresContext,
+      return NS_NewDOMPointerEvent(aOwner, aPresContext,
                                    aEvent->AsPointerEvent());
     case eTouchEventClass:
-      return NS_NewDOMTouchEvent(aDOMEvent, aOwner, aPresContext,
-                                 aEvent->AsTouchEvent());
+      return NS_NewDOMTouchEvent(aOwner, aPresContext, aEvent->AsTouchEvent());
     case eTransitionEventClass:
-      return NS_NewDOMTransitionEvent(aDOMEvent, aOwner, aPresContext,
+      return NS_NewDOMTransitionEvent(aOwner, aPresContext,
                                       aEvent->AsTransitionEvent());
     case eAnimationEventClass:
-      return NS_NewDOMAnimationEvent(aDOMEvent, aOwner, aPresContext,
+      return NS_NewDOMAnimationEvent(aOwner, aPresContext,
                                      aEvent->AsAnimationEvent());
     default:
       // For all other types of events, create a vanilla event object.
-      return NS_NewDOMEvent(aDOMEvent, aOwner, aPresContext, aEvent);
+      return NS_NewDOMEvent(aOwner, aPresContext, aEvent);
     }
   }
 
   // And if we didn't get an event, check the type argument.
 
   if (aEventType.LowerCaseEqualsLiteral("mouseevent") ||
       aEventType.LowerCaseEqualsLiteral("mouseevents") ||
       aEventType.LowerCaseEqualsLiteral("popupevents"))
-    return NS_NewDOMMouseEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMMouseEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("mousescrollevents"))
-    return NS_NewDOMMouseScrollEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMMouseScrollEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("dragevent") ||
       aEventType.LowerCaseEqualsLiteral("dragevents"))
-    return NS_NewDOMDragEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMDragEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("keyboardevent") ||
       aEventType.LowerCaseEqualsLiteral("keyevents"))
-    return NS_NewDOMKeyboardEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMKeyboardEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("compositionevent") ||
       aEventType.LowerCaseEqualsLiteral("textevent") ||
       aEventType.LowerCaseEqualsLiteral("textevents")) {
-    return NS_NewDOMCompositionEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMCompositionEvent(aOwner, aPresContext, nullptr);
   }
   if (aEventType.LowerCaseEqualsLiteral("mutationevent") ||
         aEventType.LowerCaseEqualsLiteral("mutationevents"))
-    return NS_NewDOMMutationEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMMutationEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("deviceorientationevent")) {
     DeviceOrientationEventInit init;
-    nsRefPtr<DeviceOrientationEvent> event =
-      DeviceOrientationEvent::Constructor(aOwner, EmptyString(), init);
-    event.forget(aDOMEvent);
-    return NS_OK;
+    return DeviceOrientationEvent::Constructor(aOwner, EmptyString(), init);
   }
   if (aEventType.LowerCaseEqualsLiteral("devicemotionevent"))
-    return NS_NewDOMDeviceMotionEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMDeviceMotionEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("uievent") ||
       aEventType.LowerCaseEqualsLiteral("uievents"))
-    return NS_NewDOMUIEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMUIEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("event") ||
       aEventType.LowerCaseEqualsLiteral("events") ||
       aEventType.LowerCaseEqualsLiteral("htmlevents") ||
       aEventType.LowerCaseEqualsLiteral("svgevent") ||
       aEventType.LowerCaseEqualsLiteral("svgevents"))
-    return NS_NewDOMEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("svgzoomevent") ||
       aEventType.LowerCaseEqualsLiteral("svgzoomevents"))
-    return NS_NewDOMSVGZoomEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMSVGZoomEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("timeevent") ||
       aEventType.LowerCaseEqualsLiteral("timeevents"))
-    return NS_NewDOMTimeEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMTimeEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("xulcommandevent") ||
       aEventType.LowerCaseEqualsLiteral("xulcommandevents"))
-    return NS_NewDOMXULCommandEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMXULCommandEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("commandevent") ||
       aEventType.LowerCaseEqualsLiteral("commandevents"))
-    return NS_NewDOMCommandEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMCommandEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("datacontainerevent") ||
       aEventType.LowerCaseEqualsLiteral("datacontainerevents"))
-    return NS_NewDOMDataContainerEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMDataContainerEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("messageevent"))
-    return NS_NewDOMMessageEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMMessageEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("notifypaintevent"))
-    return NS_NewDOMNotifyPaintEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMNotifyPaintEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("simplegestureevent"))
-    return NS_NewDOMSimpleGestureEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMSimpleGestureEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("beforeunloadevent"))
-    return NS_NewDOMBeforeUnloadEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMBeforeUnloadEvent(aOwner, aPresContext, nullptr);
   // XXXkhuey this is broken
   if (aEventType.LowerCaseEqualsLiteral("pagetransition")) {
     PageTransitionEventInit init;
-    nsRefPtr<PageTransitionEvent> event =
-      PageTransitionEvent::Constructor(aOwner, EmptyString(), init);
-    event.forget(aDOMEvent);
-    return NS_OK;
+    return PageTransitionEvent::Constructor(aOwner, EmptyString(), init);
   }
   if (aEventType.LowerCaseEqualsLiteral("scrollareaevent"))
-    return NS_NewDOMScrollAreaEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMScrollAreaEvent(aOwner, aPresContext, nullptr);
   // XXXkhuey Chrome supports popstateevent here, even though it provides no
   // initPopStateEvent method.  This is nuts ... but copying it is unlikely to
   // break the web.
   if (aEventType.LowerCaseEqualsLiteral("popstateevent")) {
     AutoJSContext cx;
     RootedDictionary<PopStateEventInit> init(cx);
-    nsRefPtr<PopStateEvent> event =
-      PopStateEvent::Constructor(aOwner, EmptyString(), init);
-    event.forget(aDOMEvent);
-    return NS_OK;
+    return PopStateEvent::Constructor(aOwner, EmptyString(), init);
   }
   if (aEventType.LowerCaseEqualsLiteral("touchevent") &&
       TouchEvent::PrefEnabled())
-    return NS_NewDOMTouchEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMTouchEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("hashchangeevent")) {
     HashChangeEventInit init;
-    nsRefPtr<HashChangeEvent> event =
-      HashChangeEvent::Constructor(aOwner, EmptyString(), init);
-    event.forget(aDOMEvent);
-    return NS_OK;
+    return HashChangeEvent::Constructor(aOwner, EmptyString(), init);
   }
   if (aEventType.LowerCaseEqualsLiteral("customevent"))
-    return NS_NewDOMCustomEvent(aDOMEvent, aOwner, aPresContext, nullptr);
+    return NS_NewDOMCustomEvent(aOwner, aPresContext, nullptr);
   if (aEventType.LowerCaseEqualsLiteral("storageevent")) {
-    return NS_NewDOMStorageEvent(aDOMEvent, aOwner);
+    return NS_NewDOMStorageEvent(aOwner);
   }
 
 
   // NEW EVENT TYPES SHOULD NOT BE ADDED HERE; THEY SHOULD USE ONLY EVENT
   // CONSTRUCTORS
 
-  return NS_ERROR_DOM_NOT_SUPPORTED_ERR;
+  return nullptr;
 }
 
 } // namespace mozilla

--- a/dom/events/EventDispatcher.h
+++ b/dom/events/EventDispatcher.h
@@ -18,16 +18,17 @@
 class nsIContent;
 class nsIDOMEvent;
 class nsPresContext;
 
 template<class E> class nsCOMArray;
 
 namespace mozilla {
 namespace dom {
+class Event;
 class EventTarget;
 } // namespace dom
 
 /**
  * About event dispatching:
  * When either EventDispatcher::Dispatch or
  * EventDispatcher::DispatchDOMEvent is called an event target chain is
  * created. EventDispatcher creates the chain by calling PreHandleEvent 
@@ -267,23 +268,22 @@ public:
    */
   static nsresult DispatchDOMEvent(nsISupports* aTarget,
                                    WidgetEvent* aEvent,
                                    nsIDOMEvent* aDOMEvent,
                                    nsPresContext* aPresContext,
                                    nsEventStatus* aEventStatus);
 
   /**
-   * Creates a DOM Event.
+   * Creates a DOM Event.  Returns null if the event type is unsupported.
    */
-  static nsresult CreateEvent(dom::EventTarget* aOwner,
-                              nsPresContext* aPresContext,
-                              WidgetEvent* aEvent,
-                              const nsAString& aEventType,
-                              nsIDOMEvent** aDOMEvent);
+  static already_AddRefed<dom::Event> CreateEvent(dom::EventTarget* aOwner,
+                                                  nsPresContext* aPresContext,
+                                                  WidgetEvent* aEvent,
+                                                  const nsAString& aEventType);
 
   /**
    * Called at shutting down.
    */
   static void Shutdown();
 };
 
 } // namespace mozilla

--- a/dom/events/EventListenerManager.cpp
+++ b/dom/events/EventListenerManager.cpp
@@ -1104,18 +1104,20 @@ EventListenerManager::HandleEventInterna
       hasListener = true;
       if (listener->IsListening(aEvent) &&
           (aEvent->mFlags.mIsTrusted ||
            listener->mFlags.mAllowUntrustedEvents)) {
         if (!*aDOMEvent) {
           // This is tiny bit slow, but happens only once per event.
           nsCOMPtr<EventTarget> et =
             do_QueryInterface(aEvent->originalTarget);
-          EventDispatcher::CreateEvent(et, aPresContext,
-                                       aEvent, EmptyString(), aDOMEvent);
+          nsRefPtr<Event> event = EventDispatcher::CreateEvent(et, aPresContext,
+                                                               aEvent,
+                                                               EmptyString());
+          event.forget(aDOMEvent);
         }
         if (*aDOMEvent) {
           if (!aEvent->currentTarget) {
             aEvent->currentTarget = aCurrentTarget->GetTargetForDOMEvent();
             if (!aEvent->currentTarget) {
               break;
             }
           }

--- a/dom/events/EventStateManager.cpp
+++ b/dom/events/EventStateManager.cpp
@@ -11,16 +11,17 @@
 #include "mozilla/IMEStateManager.h"
 #include "mozilla/MiscEvents.h"
 #include "mozilla/MathAlgorithms.h"
 #include "mozilla/MouseEvents.h"
 #include "mozilla/TextComposition.h"
 #include "mozilla/TextEvents.h"
 #include "mozilla/TouchEvents.h"
 #include "mozilla/dom/ContentChild.h"
+#include "mozilla/dom/DragEvent.h"
 #include "mozilla/dom/Event.h"
 #include "mozilla/dom/TabParent.h"
 #include "mozilla/dom/UIEvent.h"
 
 #include "ContentEventHandler.h"
 #include "IMEContentObserver.h"
 #include "WheelHandlingHelper.h"
 
@@ -49,17 +50,16 @@
 #include "nsIContentViewer.h"
 #include "nsFrameManager.h"
 
 #include "nsIDOMXULElement.h"
 #include "nsIDOMKeyEvent.h"
 #include "nsIObserverService.h"
 #include "nsIDocShell.h"
 #include "nsIDOMWheelEvent.h"
-#include "nsIDOMDragEvent.h"
 #include "nsIDOMUIEvent.h"
 #include "nsIMozBrowserFrame.h"
 
 #include "nsSubDocumentFrame.h"
 #include "nsLayoutUtils.h"
 #include "nsIInterfaceRequestorUtils.h"
 #include "nsUnicharUtils.h"
 #include "nsContentUtils.h"
@@ -1876,32 +1876,26 @@ EventStateManager::DoDefaultDragStart(ns
   nsCOMPtr<nsISupportsArray> transArray =
     aDataTransfer->GetTransferables(dragTarget->AsDOMNode());
   if (!transArray)
     return false;
 
   // XXXndeakin don't really want to create a new drag DOM event
   // here, but we need something to pass to the InvokeDragSession
   // methods.
-  nsCOMPtr<nsIDOMEvent> domEvent;
-  NS_NewDOMDragEvent(getter_AddRefs(domEvent), dragTarget,
-                     aPresContext, aDragEvent);
-
-  nsCOMPtr<nsIDOMDragEvent> domDragEvent = do_QueryInterface(domEvent);
-  // if creating a drag event failed, starting a drag session will
-  // just fail.
+  nsRefPtr<DragEvent> event =
+    NS_NewDOMDragEvent(dragTarget, aPresContext, aDragEvent);
 
   // Use InvokeDragSessionWithSelection if a selection is being dragged,
   // such that the image can be generated from the selected text. However,
   // use InvokeDragSessionWithImage if a custom image was set or something
   // other than a selection is being dragged.
   if (!dragImage && aSelection) {
     dragService->InvokeDragSessionWithSelection(aSelection, transArray,
-                                                action, domDragEvent,
-                                                aDataTransfer);
+                                                action, event, aDataTransfer);
   }
   else {
     // if dragging within a XUL tree and no custom drag image was
     // set, the region argument to InvokeDragSessionWithImage needs
     // to be set to the area encompassing the selected rows of the
     // tree to ensure that the drag feedback gets clipped to those
     // rows. For other content, region should be null.
     nsCOMPtr<nsIScriptableRegion> region;
@@ -1917,18 +1911,17 @@ EventStateManager::DoDefaultDragStart(ns
       }
     }
 #endif
 
     dragService->InvokeDragSessionWithImage(dragTarget->AsDOMNode(), transArray,
                                             region, action,
                                             dragImage ? dragImage->AsDOMNode() :
                                                         nullptr,
-                                            imageX,
-                                            imageY, domDragEvent,
+                                            imageX, imageY, event,
                                             aDataTransfer);
   }
 
   return true;
 }
 
 nsresult
 EventStateManager::GetContentViewer(nsIContentViewer** aCv)

--- a/dom/events/FocusEvent.cpp
+++ b/dom/events/FocusEvent.cpp
@@ -72,19 +72,16 @@ FocusEvent::Constructor(const GlobalObje
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMFocusEvent(nsIDOMEvent** aInstancePtrResult,
-                    EventTarget* aOwner,
+already_AddRefed<FocusEvent>
+NS_NewDOMFocusEvent(EventTarget* aOwner,
                     nsPresContext* aPresContext,
                     InternalFocusEvent* aEvent)
 {
-  FocusEvent* it = new FocusEvent(aOwner, aPresContext, aEvent);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<FocusEvent> it = new FocusEvent(aOwner, aPresContext, aEvent);
+  return it.forget();
 }

--- a/dom/events/FocusEvent.h
+++ b/dom/events/FocusEvent.h
@@ -48,9 +48,14 @@ protected:
                           nsIDOMWindow* aView,
                           int32_t aDetail,
                           EventTarget* aRelatedTarget);
 };
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::FocusEvent>
+NS_NewDOMFocusEvent(mozilla::dom::EventTarget* aOwner,
+                    nsPresContext* aPresContext,
+                    mozilla::InternalFocusEvent* aEvent);
+
 #endif // mozilla_dom_FocusEvent_h_

--- a/dom/events/InputEvent.cpp
+++ b/dom/events/InputEvent.cpp
@@ -58,19 +58,16 @@ InputEvent::Constructor(const GlobalObje
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMInputEvent(nsIDOMEvent** aInstancePtrResult,
-                    EventTarget* aOwner,
+already_AddRefed<InputEvent>
+NS_NewDOMInputEvent(EventTarget* aOwner,
                     nsPresContext* aPresContext,
                     InternalEditorInputEvent* aEvent)
 {
-  InputEvent* it = new InputEvent(aOwner, aPresContext, aEvent);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<InputEvent> it = new InputEvent(aOwner, aPresContext, aEvent);
+  return it.forget();
 }

--- a/dom/events/InputEvent.h
+++ b/dom/events/InputEvent.h
@@ -41,9 +41,14 @@ public:
 
 protected:
   ~InputEvent() {}
 };
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::InputEvent>
+NS_NewDOMInputEvent(mozilla::dom::EventTarget* aOwner,
+                    nsPresContext* aPresContext,
+                    mozilla::InternalEditorInputEvent* aEvent);
+
 #endif // mozilla_dom_InputEvent_h_

--- a/dom/events/KeyboardEvent.cpp
+++ b/dom/events/KeyboardEvent.cpp
@@ -304,19 +304,16 @@ KeyboardEvent::InitKeyEvent(const nsAStr
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMKeyboardEvent(nsIDOMEvent** aInstancePtrResult,
-                       EventTarget* aOwner,
+already_AddRefed<KeyboardEvent>
+NS_NewDOMKeyboardEvent(EventTarget* aOwner,
                        nsPresContext* aPresContext,
                        WidgetKeyboardEvent* aEvent)
 {
-  KeyboardEvent* it = new KeyboardEvent(aOwner, aPresContext, aEvent);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<KeyboardEvent> it = new KeyboardEvent(aOwner, aPresContext, aEvent);
+  return it.forget();
 }

--- a/dom/events/KeyboardEvent.h
+++ b/dom/events/KeyboardEvent.h
@@ -88,9 +88,14 @@ private:
   // value.  mInitializedWhichValue stores it.  I.e., this is invalid when
   // mInitializedByCtor is false.
   uint32_t mInitializedWhichValue;
 };
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::KeyboardEvent>
+NS_NewDOMKeyboardEvent(mozilla::dom::EventTarget* aOwner,
+                       nsPresContext* aPresContext,
+                       mozilla::WidgetKeyboardEvent* aEvent);
+
 #endif // mozilla_dom_KeyboardEvent_h_

--- a/dom/events/MessageEvent.cpp
+++ b/dom/events/MessageEvent.cpp
@@ -167,17 +167,17 @@ MessageEvent::Constructor(EventTarget* a
   }
 
   if (aParam.mPorts.WasPassed() && !aParam.mPorts.Value().IsNull()) {
     nsTArray<nsRefPtr<MessagePortBase>> ports;
     for (uint32_t i = 0, len = aParam.mPorts.Value().Value().Length(); i < len; ++i) {
       ports.AppendElement(aParam.mPorts.Value().Value()[i].get());
     }
 
-    event->mPorts = new MessagePortList(static_cast<EventBase*>(event), ports);
+    event->mPorts = new MessagePortList(static_cast<Event*>(event), ports);
   }
 
   return event.forget();
 }
 
 NS_IMETHODIMP
 MessageEvent::InitMessageEvent(const nsAString& aType,
                                bool aCanBubble,
@@ -219,19 +219,16 @@ MessageEvent::SetSource(mozilla::dom::wo
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMMessageEvent(nsIDOMEvent** aInstancePtrResult,
-                      EventTarget* aOwner,
+already_AddRefed<MessageEvent>
+NS_NewDOMMessageEvent(EventTarget* aOwner,
                       nsPresContext* aPresContext,
                       WidgetEvent* aEvent) 
 {
-  MessageEvent* it = new MessageEvent(aOwner, aPresContext, aEvent);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<MessageEvent> it = new MessageEvent(aOwner, aPresContext, aEvent);
+  return it.forget();
 }

--- a/dom/events/MessageEvent.h
+++ b/dom/events/MessageEvent.h
@@ -97,9 +97,14 @@ private:
   nsRefPtr<MessagePortBase> mPortSource;
   nsRefPtr<workers::ServiceWorkerClient> mClientSource;
   nsRefPtr<MessagePortList> mPorts;
 };
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::MessageEvent>
+NS_NewDOMMessageEvent(mozilla::dom::EventTarget* aOwner,
+                      nsPresContext* aPresContext,
+                      mozilla::WidgetEvent* aEvent);
+
 #endif // mozilla_dom_MessageEvent_h_

--- a/dom/events/MouseEvent.cpp
+++ b/dom/events/MouseEvent.cpp
@@ -499,19 +499,16 @@ MouseEvent::GetMozInputSource(uint16_t* 
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMMouseEvent(nsIDOMEvent** aInstancePtrResult,
-                    EventTarget* aOwner,
+already_AddRefed<MouseEvent>
+NS_NewDOMMouseEvent(EventTarget* aOwner,
                     nsPresContext* aPresContext,
                     WidgetMouseEvent* aEvent)
 {
-  MouseEvent* it = new MouseEvent(aOwner, aPresContext, aEvent);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<MouseEvent> it = new MouseEvent(aOwner, aPresContext, aEvent);
+  return it.forget();
 }

--- a/dom/events/MouseEvent.h
+++ b/dom/events/MouseEvent.h
@@ -127,9 +127,14 @@ protected:
 
 } // namespace dom
 } // namespace mozilla
 
 #define NS_FORWARD_TO_MOUSEEVENT \
   NS_FORWARD_NSIDOMMOUSEEVENT(MouseEvent::) \
   NS_FORWARD_TO_UIEVENT
 
+already_AddRefed<mozilla::dom::MouseEvent>
+NS_NewDOMMouseEvent(mozilla::dom::EventTarget* aOwner,
+                    nsPresContext* aPresContext,
+                    mozilla::WidgetMouseEvent* aEvent);
+
 #endif // mozilla_dom_MouseEvent_h_

--- a/dom/events/MouseScrollEvent.cpp
+++ b/dom/events/MouseScrollEvent.cpp
@@ -83,19 +83,17 @@ MouseScrollEvent::Axis()
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace dom;
 
-nsresult
-NS_NewDOMMouseScrollEvent(nsIDOMEvent** aInstancePtrResult,
-                          EventTarget* aOwner,
+already_AddRefed<MouseScrollEvent>
+NS_NewDOMMouseScrollEvent(EventTarget* aOwner,
                           nsPresContext* aPresContext,
                           WidgetMouseScrollEvent* aEvent)
 {
-  MouseScrollEvent* it = new MouseScrollEvent(aOwner, aPresContext, aEvent);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<MouseScrollEvent> it =
+    new MouseScrollEvent(aOwner, aPresContext, aEvent);
+  return it.forget();
 }

--- a/dom/events/MouseScrollEvent.h
+++ b/dom/events/MouseScrollEvent.h
@@ -54,9 +54,14 @@ public:
 
 protected:
   ~MouseScrollEvent() {}
 };
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::MouseScrollEvent>
+NS_NewDOMMouseScrollEvent(mozilla::dom::EventTarget* aOwner,
+                          nsPresContext* aPresContext,
+                          mozilla::WidgetMouseScrollEvent* aEvent);
+
 #endif // mozilla_dom_MouseScrollEvent_h_

--- a/dom/events/MutationEvent.cpp
+++ b/dom/events/MutationEvent.cpp
@@ -114,19 +114,16 @@ MutationEvent::InitMutationEvent(const n
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMMutationEvent(nsIDOMEvent** aInstancePtrResult,
-                       EventTarget* aOwner,
+already_AddRefed<MutationEvent>
+NS_NewDOMMutationEvent(EventTarget* aOwner,
                        nsPresContext* aPresContext,
                        InternalMutationEvent* aEvent) 
 {
-  MutationEvent* it = new MutationEvent(aOwner, aPresContext, aEvent);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<MutationEvent> it = new MutationEvent(aOwner, aPresContext, aEvent);
+  return it.forget();
 }

--- a/dom/events/MutationEvent.h
+++ b/dom/events/MutationEvent.h
@@ -60,9 +60,14 @@ public:
 
 protected:
   ~MutationEvent() {}
 };
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::MutationEvent>
+NS_NewDOMMutationEvent(mozilla::dom::EventTarget* aOwner,
+                       nsPresContext* aPresContext,
+                       mozilla::InternalMutationEvent* aEvent);
+
 #endif // mozilla_dom_MutationEvent_h_

--- a/dom/events/NotifyPaintEvent.cpp
+++ b/dom/events/NotifyPaintEvent.cpp
@@ -157,22 +157,20 @@ NotifyPaintEvent::Deserialize(const IPC:
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMNotifyPaintEvent(nsIDOMEvent** aInstancePtrResult,
-                          EventTarget* aOwner,
+already_AddRefed<NotifyPaintEvent>
+NS_NewDOMNotifyPaintEvent(EventTarget* aOwner,
                           nsPresContext* aPresContext,
                           WidgetEvent* aEvent,
                           uint32_t aEventType,
                           nsInvalidateRequestList* aInvalidateRequests) 
 {
-  NotifyPaintEvent* it = new NotifyPaintEvent(aOwner, aPresContext, aEvent,
-                                              aEventType, aInvalidateRequests);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<NotifyPaintEvent> it =
+    new NotifyPaintEvent(aOwner, aPresContext, aEvent, aEventType,
+                         aInvalidateRequests);
+  return it.forget();
 }

--- a/dom/events/NotifyPaintEvent.h
+++ b/dom/events/NotifyPaintEvent.h
@@ -62,9 +62,17 @@ private:
   nsRegion GetRegion();
 
   nsTArray<nsInvalidateRequestList::Request> mInvalidateRequests;
 };
 
 } // namespace dom
 } // namespace mozilla
 
+// This empties aInvalidateRequests.
+already_AddRefed<mozilla::dom::NotifyPaintEvent>
+NS_NewDOMNotifyPaintEvent(mozilla::dom::EventTarget* aOwner,
+                          nsPresContext* aPresContext,
+                          mozilla::WidgetEvent* aEvent,
+                          uint32_t aEventType = 0,
+                          nsInvalidateRequestList* aInvalidateRequests = nullptr);
+
 #endif // mozilla_dom_NotifyPaintEvent_h_

--- a/dom/events/PointerEvent.cpp
+++ b/dom/events/PointerEvent.cpp
@@ -159,19 +159,16 @@ PointerEvent::IsPrimary()
 }
 
 } // namespace dom
 } // namespace mozilla
 
 using namespace mozilla;
 using namespace mozilla::dom;
 
-nsresult
-NS_NewDOMPointerEvent(nsIDOMEvent** aInstancePtrResult,
-                      EventTarget* aOwner,
+already_AddRefed<PointerEvent>
+NS_NewDOMPointerEvent(EventTarget* aOwner,
                       nsPresContext* aPresContext,
                       WidgetPointerEvent *aEvent)
 {
-  PointerEvent *it = new PointerEvent(aOwner, aPresContext, aEvent);
-  NS_ADDREF(it);
-  *aInstancePtrResult = static_cast<Event*>(it);
-  return NS_OK;
+  nsRefPtr<PointerEvent> it = new PointerEvent(aOwner, aPresContext, aEvent);
+  return it.forget();
 }

--- a/dom/events/PointerEvent.h
+++ b/dom/events/PointerEvent.h
@@ -50,9 +50,14 @@ public:
   void GetPointerType(nsAString& aPointerType);
 };
 
 void ConvertPointerTypeToString(uint16_t aPointerTypeSrc, nsAString& aPointerTypeDest);
 
 } // namespace dom
 } // namespace mozilla
 
+already_AddRefed<mozilla::dom::PointerEvent>
+NS_NewDOMPointerEvent(mozilla::dom::EventTarget* aOwner,
+                      nsPresContext* aPresContext,
+                      mozilla::WidgetPointerEvent* aEvent);
+
 #endif // mozilla_dom_PointerEvent_h_