Add support for BeforeUnloadEvent

Source/core/page/UseCounter.cpp

 
 /*
  * Copyright (C) 2012 Google, Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 648 matching lines @@
 
     case ReleaseEvents:
         return "releaseEvents() is deprecated. This method doesn't do anything.";
 
     case ConsoleMarkTimeline:
         return "console.markTimeline is deprecated. Please use the console.timeStamp instead.";
 
     case FileError:
         return "FileError is deprecated. Please use the 'name' or 'message' attributes of DOMError rather than 'code'.";
 
+    case EventReturnValue:
+        return "event.returnValue is deprecated. Please use the standard event.preventDefault() instead.";
+
     // Features that aren't deprecated don't have a deprecation message.
     default:
         return String();
     }
 }
 
 void UseCounter::count(CSSPropertyID feature)
 {
     ASSERT(feature >= firstCSSProperty);
     ASSERT(feature <= lastCSSProperty);
@@ skipping 23 matching lines @@
 UseCounter* UseCounter::getFrom(const StyleSheetContents* sheetContents)
 {
     // FIXME: We may want to handle stylesheets that have multiple owners
     //        http://crbug.com/242125
     if (sheetContents && !sheetContents->isUserStyleSheet() && sheetContents->hasSingleOwnerNode())
         return getFrom(sheetContents->singleOwnerDocument());
     return 0;
 }
 
 } // namespace WebCore