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

Source/modules/mediasource/WebKitSourceBuffer.idl

 /*
  * 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 12 matching lines @@
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
  
 [
     NoInterfaceObject,
-    EnabledAtRuntime=mediaSource
-] interface SourceBuffer {
+    EnabledAtRuntime=webKitMediaSource
+] interface WebKitSourceBuffer {
 
     // Returns the time ranges buffered.
     [GetterRaisesException] readonly attribute TimeRanges buffered;
 
     // Applies an offset to media segment timestamps.
     [SetterRaisesException] attribute double timestampOffset;
 
     // Append segment data.
     [RaisesException] void append(Uint8Array data);
 
     // Abort the current segment append sequence.
     [RaisesException] void abort();
 };