Remove the webkit prefix from idl properties and interfaces.

sky/engine/core/html/HTMLMediaElement.idl

Index: sky/engine/core/html/HTMLMediaElement.idl
diff --git a/sky/engine/core/html/HTMLMediaElement.idl b/sky/engine/core/html/HTMLMediaElement.idl
index 54b00980bbc761b7a8f6dc91729f18398d7edebb..c60b843566da813fd765c2aef735cfe093f4961a 100644
--- a/sky/engine/core/html/HTMLMediaElement.idl
+++ b/sky/engine/core/html/HTMLMediaElement.idl
@@ -82,11 +82,5 @@
     attribute boolean muted;
     [Reflect=muted] attribute boolean defaultMuted;
 
-    // WebKit extensions
-
-    // The number of bytes consumed by the media decoder.
-    [MeasureAs=PrefixedAudioDecodedByteCount] readonly attribute unsigned long webkitAudioDecodedByteCount;
-    [MeasureAs=PrefixedVideoDecodedByteCount] readonly attribute unsigned long webkitVideoDecodedByteCount;
-
     [Reflect, RuntimeEnabled=SubresourceIntegrity] attribute DOMString integrity;
 };