Revert 124780 - Create a MediaSource object.

Source/WebCore/page/DOMWindow.idl

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2011 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 767 matching lines @@
 
         attribute [Conditional=BLOB|FILE_SYSTEM] FileErrorConstructor FileError;
         attribute [Conditional=BLOB] FileReaderConstructor FileReader;
 
         attribute [Conditional=BLOB&LEGACY_WEBKIT_BLOB_BUILDER] WebKitBlobBuilderConstructor WebKitBlobBuilder;
 
         attribute [Conditional=BLOB] DOMURLConstructor webkitURL;
 
         attribute [Conditional=MUTATION_OBSERVERS] MutationObserverConstructor WebKitMutationObserver;
 
-        attribute [Conditional=MEDIA_SOURCE, V8EnabledAtRuntime=mediaSource] MediaSourceConstructor MediaSource;
         attribute [Conditional=MEDIA_SOURCE, V8EnabledAtRuntime=mediaSource] SourceBufferConstructor SourceBuffer;
         attribute [Conditional=MEDIA_SOURCE, V8EnabledAtRuntime=mediaSource] SourceBufferListConstructor SourceBufferList;
 
 #endif // defined(LANGUAGE_JAVASCRIPT)
 
 #if defined(V8_BINDING) && V8_BINDING
         // window.toString() requires special handling in V8
         [V8DoNotCheckSignature, DoNotCheckSecurity, Custom, NotEnumerable] DOMString toString();
 #endif // defined(V8_BINDING)
     };
 
 }