--- a/browser/base/content/test/static/browser_misused_characters_in_strings.js
+++ b/browser/base/content/test/static/browser_misused_characters_in_strings.js
@@ -85,21 +85,16 @@ let gWhitelist = [
     type: "double-quote",
   },
   {
     file: "layout_errors.properties",
     key: "ImageMapPolyOddNumberOfCoords",
     type: "double-quote",
   },
   {
-    file: "xbl.properties",
-    key: "CommandNotInChrome",
-    type: "double-quote",
-  },
-  {
     file: "dom.properties",
     key: "PatternAttributeCompileFailure",
     type: "single-quote",
   },
   // dom.properties is packaged twice so we need to have two exceptions for this string.
   {
     file: "dom.properties",
     key: "PatternAttributeCompileFailure",

--- a/dom/base/nsContentUtils.cpp
+++ b/dom/base/nsContentUtils.cpp
@@ -3545,17 +3545,16 @@ void nsContentUtils::GetEventArgNames(in
   }
 }
 
 // Note: The list of content bundles in nsStringBundle.cpp should be updated
 // whenever entries are added or removed from this list.
 static const char* gPropertiesFiles[nsContentUtils::PropertiesFile_COUNT] = {
     // Must line up with the enum values in |PropertiesFile| enum.
     "chrome://global/locale/css.properties",
-    "chrome://global/locale/xbl.properties",
     "chrome://global/locale/xul.properties",
     "chrome://global/locale/layout_errors.properties",
     "chrome://global/locale/layout/HtmlForm.properties",
     "chrome://global/locale/printing.properties",
     "chrome://global/locale/dom/dom.properties",
     "chrome://global/locale/layout/htmlparser.properties",
     "chrome://global/locale/svg/svg.properties",
     "chrome://branding/locale/brand.properties",

--- a/dom/base/nsContentUtils.h
+++ b/dom/base/nsContentUtils.h
@@ -1080,17 +1080,16 @@ class nsContentUtils {
    *   @param [aLineNumber=0] (Optional) Line number within resource
               containing error.
    *   @param [aColumnNumber=0] (Optional) Column number within resource
               containing error.
               If aURI is null, then aDocument->GetDocumentURI() is used.
    */
   enum PropertiesFile {
     eCSS_PROPERTIES,
-    eXBL_PROPERTIES,
     eXUL_PROPERTIES,
     eLAYOUT_PROPERTIES,
     eFORMS_PROPERTIES,
     ePRINTING_PROPERTIES,
     eDOM_PROPERTIES,
     eHTMLPARSER_PROPERTIES,
     eSVG_PROPERTIES,
     eBRAND_PROPERTIES,

--- a/dom/events/KeyEventHandler.cpp
+++ b/dom/events/KeyEventHandler.cpp
@@ -675,20 +675,20 @@ void KeyEventHandler::ReportKeyConflict(
   nsCOMPtr<Document> doc = aKeyElement->OwnerDoc();
 
   nsAutoString id;
   aKeyElement->GetAttr(kNameSpaceID_None, nsGkAtoms::id, id);
   AutoTArray<nsString, 3> params;
   params.AppendElement(aKey);
   params.AppendElement(aModifiers);
   params.AppendElement(id);
-  nsContentUtils::ReportToConsole(
-      nsIScriptError::warningFlag, NS_LITERAL_CSTRING("XBL Prototype Handler"),
-      doc, nsContentUtils::eXBL_PROPERTIES, aMessageName, params, nullptr,
-      EmptyString(), 0);
+  nsContentUtils::ReportToConsole(nsIScriptError::warningFlag,
+                                  NS_LITERAL_CSTRING("Key Event Handler"), doc,
+                                  nsContentUtils::eDOM_PROPERTIES, aMessageName,
+                                  params, nullptr, EmptyString(), 0);
 }
 
 bool KeyEventHandler::ModifiersMatchMask(
     UIEvent* aEvent, const IgnoreModifierState& aIgnoreModifierState) {
   WidgetInputEvent* inputEvent = aEvent->WidgetEventPtr()->AsInputEvent();
   NS_ENSURE_TRUE(inputEvent, false);
 
   if (mKeyMask & cMetaMask) {

--- a/dom/locales/en-US/chrome/dom/dom.properties
+++ b/dom/locales/en-US/chrome/dom/dom.properties
@@ -341,16 +341,19 @@ MixedDisplayObjectSubrequestWarning=Load
 MotionEventWarning=Use of the motion sensor is deprecated.
 OrientationEventWarning=Use of the orientation sensor is deprecated.
 ProximityEventWarning=Use of the proximity sensor is deprecated.
 AmbientLightEventWarning=Use of the ambient light sensor is deprecated.
 # LOCALIZATION NOTE: Do not translate "storage", "indexedDB.open" and "navigator.storage.persist()".
 IDBOpenDBOptions_StorageTypeWarning=The ‘storage’ attribute in options passed to indexedDB.open is deprecated and will soon be removed. To get persistent storage, please use navigator.storage.persist() instead.
 UnsupportedEntryTypesIgnored=Ignoring unsupported entryTypes: %S.
 AllEntryTypesIgnored=No valid entryTypes; aborting registration.
+# LOCALIZATION NOTE: do not localize key=“%S” modifiers=“%S” id=“%S”
+GTK2Conflict2=Key event not available on GTK2: key=“%S” modifiers=“%S” id=“%S”
+WinConflict2=Key event not available on some keyboard layouts: key=“%S” modifiers=“%S” id=“%S”
 
 #LOCALIZATION NOTE(DeprecatedTestingInterfaceWarning): Do not translate this message. It's just testing only.
 DeprecatedTestingInterfaceWarning=TestingDeprecatedInterface is a testing-only interface and this is its testing deprecation message.
 #LOCALIZATION NOTE(DeprecatedTestingMethodWarning): Do not translate this message. It's just testing only.
 DeprecatedTestingMethodWarning=TestingDeprecatedInterface.deprecatedMethod() is a testing-only method and this is its testing deprecation message.
 #LOCALIZATION NOTE(DeprecatedTestingAttributeWarning): Do not translate this message. It's just testing only.
 DeprecatedTestingAttributeWarning=TestingDeprecatedInterface.deprecatedAttribute is a testing-only attribute and this is its testing deprecation message.
 # LOCALIZATION NOTE (CreateImageBitmapCanvasRenderingContext2DWarning): Do not translate CanvasRenderingContext2D and createImageBitmap.

deleted file mode 100644
--- a/dom/locales/en-US/chrome/layout/xbl.properties
+++ /dev/null
@@ -1,14 +0,0 @@
-# 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/.
-
-UnexpectedElement=Unexpected <%1$S> element.
-# LOCALIZATION NOTE: do not localize key=“%S” modifiers=“%S” id=“%S”
-GTK2Conflict2=Key event not available on GTK2: key=“%S” modifiers=“%S” id=“%S”
-WinConflict2=Key event not available on some keyboard layouts: key=“%S” modifiers=“%S” id=“%S”
-TooDeepBindingRecursion=The XBL binding “%S” is already used by too many ancestor elements; not applying it to prevent infinite recursion.
-CircularExtendsBinding=Extending the XBL binding “%S” with “%S” would lead to it extending itself
-# LOCALIZATION NOTE: do not localize <handler command="…">
-CommandNotInChrome=Use of <handler command="…"> not allowed outside chrome.
-MalformedXBL = An XBL file is malformed. Did you forget the XBL namespace on the bindings tag?
-MissingIdAttr = An “id” attribute missing on the binding tag.

--- a/dom/locales/jar.mn
+++ b/dom/locales/jar.mn
@@ -1,17 +1,16 @@
 #filter substitution
 # 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/.
 
 
 @AB_CD@.jar:
   locale/@AB_CD@/global/css.properties                         (%chrome/layout/css.properties)
-  locale/@AB_CD@/global/xbl.properties                         (%chrome/layout/xbl.properties)
   locale/@AB_CD@/global/xul.properties                         (%chrome/layout/xul.properties)
   locale/@AB_CD@/global/printing.properties                    (%chrome/layout/printing.properties)
   locale/@AB_CD@/global/layout_errors.properties               (%chrome/layout/layout_errors.properties)
   locale/@AB_CD@/global/netError.dtd                           (%chrome/netError.dtd)
   locale/@AB_CD@/global/netErrorApp.dtd                        (%chrome/netErrorApp.dtd)
   locale/@AB_CD@/global/global.dtd                             (%chrome/global.dtd)
   locale/@AB_CD@/global/appstrings.properties                  (%chrome/appstrings.properties)
   locale/@AB_CD@/global/global-strres.properties               (%chrome/global-strres.properties)

--- a/dom/locales/moz.build
+++ b/dom/locales/moz.build
@@ -26,19 +26,16 @@ with Files("en-US/chrome/layout/layout_e
     BUG_COMPONENT = ("Core", "DOM: Animation")
 
 with Files("en-US/chrome/layout/MediaDocument.properties"):
     BUG_COMPONENT = ("Core", "Layout: Images, Video, and HTML Frames")
 
 with Files("en-US/chrome/layout/printing.properties"):
     BUG_COMPONENT = ("Core", "Printing: Output")
 
-with Files("en-US/chrome/layout/xbl.properties"):
-    BUG_COMPONENT = ("Core", "XBL")
-
 with Files("en-US/chrome/layout/xmlparser.properties"):
     BUG_COMPONENT = ("Core", "XML")
 
 with Files("en-US/chrome/layout/xul.properties"):
     BUG_COMPONENT = ("Core", "XUL")
 
 with Files("en-US/chrome/mathml/**"):
     BUG_COMPONENT = ("Core", "MathML")

--- a/intl/strres/nsStringBundle.cpp
+++ b/intl/strres/nsStringBundle.cpp
@@ -73,17 +73,16 @@ static const char kContentBundles[][52] 
     "chrome://global/locale/layout/HtmlForm.properties",
     "chrome://global/locale/layout/htmlparser.properties",
     "chrome://global/locale/layout_errors.properties",
     "chrome://global/locale/mathml/mathml.properties",
     "chrome://global/locale/printing.properties",
     "chrome://global/locale/security/csp.properties",
     "chrome://global/locale/security/security.properties",
     "chrome://global/locale/svg/svg.properties",
-    "chrome://global/locale/xbl.properties",
     "chrome://global/locale/xul.properties",
     "chrome://necko/locale/necko.properties",
 };
 
 static bool IsContentBundle(const nsCString& aUrl) {
   size_t index;
   return BinarySearchIf(
       kContentBundles, 0, MOZ_ARRAY_LENGTH(kContentBundles),