Measure Event.returnValue usage in more detail

Source/core/frame/UseCounter.h

 /*
  * 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 348 matching lines @@
         CanvasRenderingContext2DSetShadow = 340,
         PrefixedPerformanceClearResourceTimings = 341,
         PrefixedPerformanceSetResourceTimingBufferSize = 342,
         EventSrcElement = 343,
         EventCancelBubble = 344,
         EventPath = 345,
         EventClipboardData = 346,
         NodeIteratorDetach = 347,
         AttrNodeValue = 348,
         AttrTextContent = 349,
+        EventGetReturnValueTrue = 350,
+        EventGetReturnValueFalse = 351,
+        EventSetReturnValueTrue = 352,
+        EventSetReturnValueFalse = 353,
         // Add new features immediately above this line. Don't change assigned
         // numbers of any item, and don't reuse removed slots.
         NumberOfFeatures, // This enum value must be last.
     };
 
     // "count" sets the bit for this feature to 1. Repeated calls are ignored.
     static void count(const Document&, Feature);
     static void count(const ExecutionContext*, Feature);
     void count(CSSParserContext, CSSPropertyID);
     void count(Feature);
@@ skipping 42 matching lines @@
 
     void updateMeasurements();
 
     OwnPtr<BitVector> m_countBits;
     BitVector m_CSSFeatureBits;
 };
 
 } // namespace WebCore
 
 #endif // UseCounter_h