Add a WebRuntimeFeature for will-change

Source/web/WebRuntimeFeatures.cpp

 /*
  * Copyright (C) 2013 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 34 matching lines @@
 }
 
 void WebRuntimeFeatures::enableExperimentalFeatures(bool enable)
 {
     RuntimeEnabledFeatures::setExperimentalFeaturesEnabled(enable);
 }
 
 void WebRuntimeFeatures::enableBleedingEdgeFastPaths(bool enable)
 {
     RuntimeEnabledFeatures::setBleedingEdgeFastPathsEnabled(enable);
+    RuntimeEnabledFeatures::setCSSWillChangeEnabled(enable);
 }
 
 void WebRuntimeFeatures::enableTestOnlyFeatures(bool enable)
 {
     RuntimeEnabledFeatures::setTestFeaturesEnabled(enable);
 }
 
 void WebRuntimeFeatures::enableApplicationCache(bool enable)
 {
     RuntimeEnabledFeatures::setApplicationCacheEnabled(enable);
@@ skipping 228 matching lines @@
 {
     RuntimeEnabledFeatures::setExperimentalWebSocketEnabled(enable);
 }
 
 void WebRuntimeFeatures::enableTargetedStyleRecalc(bool enable)
 {
     RuntimeEnabledFeatures::setTargetedStyleRecalcEnabled(enable);
 }
 
 } // namespace blink