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

Source/core/page/DOMWindow.idl

Index: Source/core/page/DOMWindow.idl
diff --git a/Source/core/page/DOMWindow.idl b/Source/core/page/DOMWindow.idl
index 6fb8da4acfe6599adc739071da3a7d5890a8f240..fdc348bd11b1d89dd758a95a657f0955228ceae9 100644
--- a/Source/core/page/DOMWindow.idl
+++ b/Source/core/page/DOMWindow.idl
@@ -300,6 +300,10 @@
     attribute IDBRequestConstructor webkitIDBRequest;
     attribute IDBTransactionConstructor webkitIDBTransaction;
 
+    [EnabledAtRuntime=webKitMediaSource] attribute WebKitMediaSourceConstructor WebKitMediaSource;
+    [EnabledAtRuntime=webKitMediaSource] attribute WebKitSourceBufferConstructor WebKitSourceBuffer;
+    [EnabledAtRuntime=webKitMediaSource] attribute WebKitSourceBufferListConstructor WebKitSourceBufferList;
+
     // Constructors enabled at runtime but whose interface does not have EnabledAtRuntime
     // extended attribute.
     // FIXME: Remove these.
@@ -330,9 +334,6 @@
     // Constructors whose name does not match the interface name.
     // FIXME: Remove these once [ImplementedAs] is used and once constructor names match interface names.
     attribute ShadowRootConstructor WebKitShadowRoot;
-    [EnabledAtRuntime=mediaSource] attribute MediaSourceConstructor WebKitMediaSource;
-    [EnabledAtRuntime=mediaSource] attribute SourceBufferConstructor WebKitSourceBuffer;
-    [EnabledAtRuntime=mediaSource] attribute SourceBufferListConstructor WebKitSourceBufferList;
     [Conditional=WEB_AUDIO] attribute PannerNodeConstructor webkitAudioPannerNode;
 
     // window.toString() requires special handling in V8