Remove window.performance.webkit* (PrefixedUserTiming)

Source/core/timing/Performance.idl

Index: Source/core/timing/Performance.idl
diff --git a/Source/core/timing/Performance.idl b/Source/core/timing/Performance.idl
index b29b83e4985a310b70a50b691543816491132756..762f6b0fab5d18dae9f3ec805b4ed399d8ada27f 100644
--- a/Source/core/timing/Performance.idl
+++ b/Source/core/timing/Performance.idl
@@ -54,12 +54,6 @@ interface Performance : EventTarget {
     [RaisesException,MeasureAs=UnprefixedUserTiming] void measure(DOMString measureName, [Default=NullString] optional DOMString startMark, [Default=NullString] optional DOMString endMark);
     [MeasureAs=UnprefixedUserTiming] void clearMeasures([Default=NullString] optional DOMString measureName);
 
-    [RaisesException,DeprecateAs=PrefixedUserTiming,ImplementedAs=mark] void webkitMark(DOMString markName);
-    [DeprecateAs=PrefixedUserTiming,ImplementedAs=clearMarks] void webkitClearMarks([Default=NullString] optional  DOMString markName);
-
-    [RaisesException,DeprecateAs=PrefixedUserTiming,ImplementedAs=measure] void webkitMeasure(DOMString measureName, [Default=NullString] optional DOMString startMark, [Default=NullString] optional DOMString endMark);
-    [DeprecateAs=PrefixedUserTiming,ImplementedAs=clearMeasures] void webkitClearMeasures([Default=NullString] optional DOMString measureName);
-
     // See http://www.w3.org/TR/hr-time/ for details.
     double now();
 };