Add WebKit prefix to MediaSource,SourceBuffer, and SourceBufferList objects.

Source/core/dom/EventTarget.h

Index: Source/core/dom/EventTarget.h
diff --git a/Source/core/dom/EventTarget.h b/Source/core/dom/EventTarget.h
index 7bf80c9493ff1cca6540eb63838eb9054f49eaa3..2039839a78d08fbcbc9b6bfd62272654874e36b1 100644
--- a/Source/core/dom/EventTarget.h
+++ b/Source/core/dom/EventTarget.h
@@ -55,7 +55,6 @@ namespace WebCore {
     class MIDIInput;
     class MIDIPort;
     class MediaController;
-    class MediaSource;
     class MediaStream;
     class MessagePort;
     class NamedFlow;
@@ -66,9 +65,10 @@ namespace WebCore {
     class ScriptProcessorNode;
     class SharedWorker;
     class SharedWorkerContext;
-    class SourceBufferList;
     class TextTrack;
     class TextTrackCue;
+    class WebKitMediaSource;
+    class WebKitSourceBufferList;
     class WebSocket;
     class Worker;
     class XMLHttpRequest;