--- a/browser/installer/package-manifest.in
+++ b/browser/installer/package-manifest.in
@@ -174,16 +174,17 @@
 @BINPATH@/components/htmlparser.xpt
 @BINPATH@/components/imglib2.xpt
 @BINPATH@/components/imgicon.xpt
 @BINPATH@/components/inspector.xpt
 @BINPATH@/components/intl.xpt
 @BINPATH@/components/jar.xpt
 @BINPATH@/components/jetpack.xpt
 @BINPATH@/components/jsdservice.xpt
+@BINPATH@/components/jsdebugger.xpt
 @BINPATH@/components/layout_base.xpt
 @BINPATH@/components/layout_forms.xpt
 #ifdef NS_PRINTING
 @BINPATH@/components/layout_printing.xpt
 #endif
 @BINPATH@/components/layout_xul_tree.xpt
 @BINPATH@/components/layout_xul.xpt
 @BINPATH@/components/locale.xpt

new file mode 100644
--- /dev/null
+++ b/js/ductwork/Makefile.in
@@ -0,0 +1,49 @@
+# ***** BEGIN LICENSE BLOCK ***** 
+# Version: MPL 1.1/GPL 2.0/LGPL 2.1
+#
+# The contents of this file are subject to the Mozilla Public License Version
+# 1.1 (the "License"); you may not use this file except in compliance with
+# the License. You may obtain a copy of the License at
+# http://www.mozilla.org/MPL/
+#
+# Software distributed under the License is distributed on an "AS IS" basis,
+# WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+# for the specific language governing rights and limitations under the
+# License.
+#
+# The Original Code is the Mozilla Browser code.
+#
+# The Initial Developer of the Original Code is
+# Netscape Communications Corporation.
+# Portions created by the Initial Developer are Copyright (C) 2011
+# the Initial Developer. All Rights Reserved.
+#
+# Contributor(s):
+#  Jason Orendorff <jorendorff@mozilla.com>
+#
+# Alternatively, the contents of this file may be used under the terms of
+# either the GNU General Public License Version 2 or later (the "GPL"), or
+# the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+# in which case the provisions of the GPL or the LGPL are applicable instead
+# of those above. If you wish to allow use of your version of this file only
+# under the terms of either the GPL or the LGPL, and not to allow others to
+# use your version of this file under the terms of the MPL, indicate your
+# decision by deleting the provisions above and replace them with the notice
+# and other provisions required by the GPL or the LGPL. If you do not delete
+# the provisions above, a recipient may use your version of this file under
+# the terms of any one of the MPL, the GPL or the LGPL.
+#
+# ***** END LICENSE BLOCK *****
+
+DEPTH     = ../..
+topsrcdir = @top_srcdir@
+srcdir    = @srcdir@
+VPATH     = @srcdir@
+
+include $(topsrcdir)/config/config.mk
+
+PARALLEL_DIRS += \
+  debugger \
+  $(NULL)
+
+include $(topsrcdir)/config/rules.mk

new file mode 100644
--- /dev/null
+++ b/js/ductwork/debugger/IJSDebugger.idl
@@ -0,0 +1,52 @@
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is mozilla.org code.
+ *
+ * The Initial Developer of the Original Code is
+ *   Mozilla Foundation
+ * Portions created by the Initial Developer are Copyright (C) 2011
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Dave Camp <dcamp@mozilla.com>
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#include "nsISupports.idl"
+
+/**
+ * Do not use this interface. Instead, write:
+ *     Components.utils.import("resource://gre/modules/jsdebugger.jsm");
+ */
+[scriptable, uuid(2fc14cc6-4ed0-4bbf-a7dd-e535bf088eb5)]
+interface IJSDebugger : nsISupports
+{
+  /**
+   * Define the global Debugger constructor.
+   */
+  [implicit_jscontext]
+  void addClass();
+};

new file mode 100644
--- /dev/null
+++ b/js/ductwork/debugger/JSDebugger.cpp
@@ -0,0 +1,111 @@
+/* -*-  Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is mozilla.org code.
+ *
+ * The Initial Developer of the Original Code is
+ * The Mozilla Foundation <http://www.mozilla.org/>.
+ * Portions created by the Initial Developer are Copyright (C) 2011
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *  Dave Camp <dcamp@mozilla.com>
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#include "JSDebugger.h"
+#include "nsIXPConnect.h"
+#include "nsThreadUtils.h"
+#include "jsapi.h"
+#include "jsobj.h"
+#include "jsgc.h"
+#include "jsfriendapi.h"
+#include "jsdbgapi.h"
+#include "mozilla/ModuleUtils.h"
+#include "nsServiceManagerUtils.h"
+#include "nsMemory.h"
+
+#define JSDEBUGGER_CONTRACTID \
+  "@mozilla.org/jsdebugger;1"
+
+#define JSDEBUGGER_CID \
+{ 0x0365cbd5, 0xd46e, 0x4e94, { 0xa3, 0x9f, 0x83, 0xb6, 0x3c, 0xd1, 0xa9, 0x63 } }
+
+namespace mozilla {
+namespace jsdebugger {
+
+NS_GENERIC_FACTORY_CONSTRUCTOR(JSDebugger)
+
+NS_IMPL_ISUPPORTS1(JSDebugger, IJSDebugger)
+
+JSDebugger::JSDebugger()
+{
+}
+
+JSDebugger::~JSDebugger()
+{
+}
+
+NS_IMETHODIMP
+JSDebugger::AddClass(JSContext *cx)
+{
+  nsresult rv;
+  nsCOMPtr<nsIXPConnect> xpc = do_GetService(nsIXPConnect::GetCID(), &rv);
+
+  JSObject* global = JS_GetGlobalForScopeChain(cx);
+  if (!global) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  if (!JS_DefineDebuggerObject(cx, global)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+}
+}
+
+NS_DEFINE_NAMED_CID(JSDEBUGGER_CID);
+
+static const mozilla::Module::CIDEntry kJSDebuggerCIDs[] = {
+  { &kJSDEBUGGER_CID, false, NULL, mozilla::jsdebugger::JSDebuggerConstructor },
+  { NULL }
+};
+
+static const mozilla::Module::ContractIDEntry kJSDebuggerContracts[] = {
+  { JSDEBUGGER_CONTRACTID, &kJSDEBUGGER_CID },
+  { NULL }
+};
+
+static const mozilla::Module kJSDebuggerModule = {
+  mozilla::Module::kVersion,
+  kJSDebuggerCIDs,
+  kJSDebuggerContracts
+};
+
+NSMODULE_DEFN(jsdebugger) = &kJSDebuggerModule;

new file mode 100644
--- /dev/null
+++ b/js/ductwork/debugger/JSDebugger.h
@@ -0,0 +1,62 @@
+/* -*-  Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is mozilla.org code.
+ *
+ * The Initial Developer of the Original Code is
+ * The Mozilla Foundation <http://www.mozilla.org/>.
+ * Portions created by the Initial Developer are Copyright (C) 2011
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *  Dave Camp <dcamp@mozilla.com>
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#ifndef COMPONENTS_JSDEBUGGER_H
+#define COMPONENTS_JSDEBUGGER_H
+
+#include "IJSDebugger.h"
+
+namespace mozilla {
+namespace jsdebugger {
+
+class JSDebugger : public IJSDebugger
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_IJSDEBUGGER
+
+  JSDebugger();
+
+private:
+  ~JSDebugger();
+};
+
+}
+}
+
+#endif

new file mode 100644
--- /dev/null
+++ b/js/ductwork/debugger/Makefile.in
@@ -0,0 +1,75 @@
+# ***** BEGIN LICENSE BLOCK *****
+# Version: MPL 1.1/GPL 2.0/LGPL 2.1
+#
+# The contents of this file are subject to the Mozilla Public License Version
+# 1.1 (the "License"); you may not use this file except in compliance with
+# the License. You may obtain a copy of the License at
+# http://www.mozilla.org/MPL/
+#
+# Software distributed under the License is distributed on an "AS IS" basis,
+# WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+# for the specific language governing rights and limitations under the
+# License.
+#
+# The Original Code is mozilla.org code.
+#
+# The Initial Developer of the Original Code is
+# The Mozilla Foundation <http://www.mozilla.org/>.
+# Portions created by the Initial Developer are Copyright (C) 2011
+# the Initial Developer. All Rights Reserved.
+#
+# Contributor(s):
+#  Dave Camp <dcamp@mozilla.com>
+#
+# Alternatively, the contents of this file may be used under the terms of
+# either the GNU General Public License Version 2 or later (the "GPL"), or
+# the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+# in which case the provisions of the GPL or the LGPL are applicable instead
+# of those above. If you wish to allow use of your version of this file only
+# under the terms of either the GPL or the LGPL, and not to allow others to
+# use your version of this file under the terms of the MPL, indicate your
+# decision by deleting the provisions above and replace them with the notice
+# and other provisions required by the GPL or the LGPL. If you do not delete
+# the provisions above, a recipient may use your version of this file under
+# the terms of any one of the MPL, the GPL or the LGPL.
+#
+# ***** END LICENSE BLOCK *****
+
+DEPTH = ../../..
+topsrcdir = @top_srcdir@
+srcdir = @srcdir@
+VPATH = @srcdir@
+relativesrcdir = js/ductwork/debugger
+
+include $(DEPTH)/config/autoconf.mk
+
+MODULE = jsdebugger
+MODULE_NAME = jsdebugger
+GRE_MODULE = 1
+
+LIBRARY_NAME = jsdebugger
+XPIDL_MODULE = jsdebugger
+LIBXUL_LIBRARY = 1
+EXPORT_LIBRARY = 1
+IS_COMPONENT = 1
+
+CPPSRCS = \
+  JSDebugger.cpp \
+  $(NULL)
+
+EXTRA_DSO_LDOPTS += \
+  $(MOZ_COMPONENT_LIBS) \
+  $(MOZ_JS_LIBS) \
+  $(NULL)
+
+EXTRA_JS_MODULES = \
+  jsdebugger.jsm \
+  $(NULL)
+
+XPIDLSRCS = \
+  IJSDebugger.idl \
+  $(NULL)
+
+XPCSHELL_TESTS = tests
+
+include $(topsrcdir)/config/rules.mk

copy from toolkit/components/ctypes/ctypes.jsm
copy to js/ductwork/debugger/jsdebugger.jsm
--- a/toolkit/components/ctypes/ctypes.jsm
+++ b/js/ductwork/debugger/jsdebugger.jsm
@@ -11,46 +11,45 @@
  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  * for the specific language governing rights and limitations under the
  * License.
  *
  * The Original Code is js-ctypes.
  *
  * The Initial Developer of the Original Code is
  * The Mozilla Foundation <http://www.mozilla.org/>.
- * Portions created by the Initial Developer are Copyright (C) 2009
+ * Portions created by the Initial Developer are Copyright (C) 2011
  * the Initial Developer. All Rights Reserved.
  *
  * Contributor(s):
- *  Dan Witte <dwitte@mozilla.com>
+ *  Jason Orendorff <jorendorff@mozilla.com>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either the GNU General Public License Version 2 or later (the "GPL"), or
  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  * in which case the provisions of the GPL or the LGPL are applicable instead
  * of those above. If you wish to allow use of your version of this file only
  * under the terms of either the GPL or the LGPL, and not to allow others to
  * use your version of this file under the terms of the MPL, indicate your
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
 
-let EXPORTED_SYMBOLS = [ "ctypes" ];
+let EXPORTED_SYMBOLS = [ "Debugger" ];
 
 /*
- * This is the js module for ctypes. Import it like so:
- *   Components.utils.import("resource://gre/modules/ctypes.jsm");
+ * This is the js module for Debugger. Import it like so:
+ *   Components.utils.import("resource://gre/modules/jsdebugger.jsm");
  *
- * This will create a 'ctypes' object, which provides an interface to describe
- * and instantiate C types and call C functions from a dynamic library.
+ * This will create a 'Debugger' object, which provides an interface to debug
+ * JavaScript code running in other compartments in the same process, on the
+ * same thread.
  *
  * For documentation on the API, see:
- * https://developer.mozilla.org/en/js-ctypes/js-ctypes_reference
- *
+ *   https://wiki.mozilla.org/Debugger
  */
 
-// Initialize the ctypes object. You do not need to do this yourself.
-const init = Components.classes["@mozilla.org/jsctypes;1"].createInstance();
-init();
-
+// Initialize the Debugger object. You do not need to do this yourself.
+const init = Components.classes["@mozilla.org/jsdebugger;1"].createInstance(Components.interfaces.IJSDebugger);
+init.addClass();

new file mode 100644
--- /dev/null
+++ b/js/ductwork/debugger/tests/head_dbg.js
@@ -0,0 +1,17 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+const Cu = Components.utils;
+const Cr = Components.results;
+
+function testGlobal(aName) {
+  let systemPrincipal = Cc["@mozilla.org/systemprincipal;1"]
+    .createInstance(Ci.nsIPrincipal);
+
+  let sandbox = Cu.Sandbox(systemPrincipal);
+  Cu.evalInSandbox("this.__name = '" + aName + "'", sandbox);
+  return sandbox;
+}

new file mode 100644
--- /dev/null
+++ b/js/ductwork/debugger/tests/test_nativewrappers.js
@@ -0,0 +1,29 @@
+function run_test()
+{
+  Components.utils.import("resource://gre/modules/jsdebugger.jsm");
+  var g = testGlobal("test1");
+
+  var dbg = new Debugger();
+  dbg.addDebuggee(g);
+  dbg.onDebuggerStatement = function(aFrame) {
+    let args = aFrame["arguments"];
+    try {
+      args[0];
+      do_check_true(true);
+    } catch(ex) {
+      do_check_true(false);
+    }
+  };
+
+  g.eval("function stopMe(arg) {debugger;}");
+
+  g2 = testGlobal("test2");
+  g2.g = g;
+  g2.eval("(" + function createBadEvent() {
+    let parser = Components.classes["@mozilla.org/xmlextras/domparser;1"].createInstance(Components.interfaces.nsIDOMParser);
+    let doc = parser.parseFromString("<foo></foo>", "text/xml");
+    g.stopMe(doc.createEvent("MouseEvent"));
+  } + ")()");
+
+  dbg.enabled = false;
+}

new file mode 100644
--- /dev/null
+++ b/js/ductwork/debugger/tests/xpcshell.ini
@@ -0,0 +1,5 @@
+[DEFAULT]
+head = head_dbg.js
+tail =
+
+[test_nativewrappers.js]

--- a/testing/xpcshell/xpcshell.ini
+++ b/testing/xpcshell/xpcshell.ini
@@ -41,16 +41,17 @@ skip-if = os == "android"
 [include:testing/xpcshell/example/unit/xpcshell.ini]
 [include:xpcom/tests/unit/xpcshell.ini]
 [include:modules/libpref/test/unit/xpcshell.ini]
 [include:intl/strres/tests/unit/xpcshell.ini]
 [include:intl/unicharutil/tests/unit/xpcshell.ini]
 [include:intl/uconv/tests/unit/xpcshell.ini]
 [include:netwerk/test/unit/xpcshell.ini]
 [include:netwerk/test/httpserver/test/xpcshell.ini]
+[include:js/ductwork/debugger/tests/xpcshell.ini]
 [include:js/jetpack/tests/unit/xpcshell.ini]
 [include:js/src/xpconnect/tests/unit/xpcshell.ini]
 [include:modules/libjar/test/unit/xpcshell.ini]
 [include:extensions/cookie/test/unit/xpcshell.ini]
 [include:storage/test/unit/xpcshell.ini]
 [include:rdf/tests/unit/xpcshell.ini]
 [include:gfx/tests/unit/xpcshell.ini]
 [include:widget/tests/unit/xpcshell.ini]

--- a/toolkit/library/libxul-config.mk
+++ b/toolkit/library/libxul-config.mk
@@ -137,16 +137,17 @@ COMPONENT_LIBS += \
 	toolkitcomps \
 	pipboot \
 	pipnss \
 	appcomps \
 	jsreflect \
 	composer \
 	jetpack_s \
 	telemetry \
+	jsdebugger \
 	storagecomps \
 	$(NULL)
 
 ifdef BUILD_CTYPES
 COMPONENT_LIBS += \
 	jsctypes \
 	$(NULL)
 endif

--- a/toolkit/library/nsStaticXULComponents.cpp
+++ b/toolkit/library/nsStaticXULComponents.cpp
@@ -268,16 +268,17 @@
     OSXPROXY_MODULE                          \
     WINDOWSPROXY_MODULE                      \
     JSCTYPES_MODULE                          \
     JSREFLECT_MODULE                         \
     MODULE(jsperf)                           \
     SERVICES_CRYPTO_MODULE                   \
     MOZ_APP_COMPONENT_MODULES                \
     MODULE(nsTelemetryModule)                \
+    MODULE(jsdebugger)                       \
     /* end of list */
 
 #define MODULE(_name) \
   NSMODULE_DECL(_name);
 
 XUL_MODULES
 
 #undef MODULE

--- a/toolkit/toolkit-makefiles.sh
+++ b/toolkit/toolkit-makefiles.sh
@@ -678,16 +678,22 @@ MAKEFILES_jsctypes="
   toolkit/components/ctypes/Makefile
   toolkit/components/ctypes/tests/Makefile
 "
 
 MAKEFILES_jsreflect="
   toolkit/components/reflect/Makefile
 "
 
+MAKEFILES_jsductwork="
+  js/ductwork/Makefile
+  js/ductwork/debugger/Makefile
+  js/ductwork/debugger/tests/Makefile
+"
+
 MAKEFILES_libpr0n="
   modules/libpr0n/Makefile
   modules/libpr0n/build/Makefile
   modules/libpr0n/public/Makefile
   modules/libpr0n/src/Makefile
   modules/libpr0n/decoders/Makefile
   modules/libpr0n/decoders/icon/Makefile
   modules/libpr0n/decoders/icon/mac/Makefile
@@ -745,16 +751,17 @@ add_makefiles "
   $MAKEFILES_gfx
   $MAKEFILES_htmlparser
   $MAKEFILES_intl
   $MAKEFILES_xpconnect
   $MAKEFILES_jsipc
   $MAKEFILES_jsdebugger
   $MAKEFILES_jsctypes
   $MAKEFILES_jsreflect
+  $MAKEFILES_jsductwork
   $MAKEFILES_content
   $MAKEFILES_layout
   $MAKEFILES_libimg
   $MAKEFILES_libjar
   $MAKEFILES_libreg
   $MAKEFILES_libpref
   $MAKEFILES_mathml
   $MAKEFILES_plugin

--- a/toolkit/toolkit-tiers.mk
+++ b/toolkit/toolkit-tiers.mk
@@ -219,16 +219,18 @@ endif
 ifdef MOZ_PREF_EXTENSIONS
 tier_platform_dirs += extensions/pref
 endif
 
 tier_platform_dirs += services/crypto/component
 
 tier_platform_dirs += startupcache
 
+tier_platform_dirs += js/ductwork
+
 ifdef APP_LIBXUL_STATICDIRS
 # Applications can cheat and ask for code to be
 # built before libxul so libxul can be linked against it.
 tier_platform_staticdirs += $(APP_LIBXUL_STATICDIRS)
 endif
 ifdef APP_LIBXUL_DIRS
 # Applications can cheat and ask for code to be
 # built before libxul so it can be linked into libxul.