Revert of Implement enableFastMobileScrolling web api.

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 87 matching lines @@
 bool WebRuntimeFeatures::isPrefixedEncryptedMediaEnabled()
 {
     return RuntimeEnabledFeatures::prefixedEncryptedMediaEnabled();
 }
 
 void WebRuntimeFeatures::enableExperimentalCanvasFeatures(bool enable)
 {
     RuntimeEnabledFeatures::setExperimentalCanvasFeaturesEnabled(enable);
 }
 
-void WebRuntimeFeatures::enableFastMobileScrolling(bool enable)
-{
-    RuntimeEnabledFeatures::setFastMobileScrollingEnabled(enable);
-}
-
 void WebRuntimeFeatures::enableFastTextAutosizing(bool enable)
 {
     RuntimeEnabledFeatures::setFastTextAutosizingEnabled(enable);
 }
 
 void WebRuntimeFeatures::enableFileSystem(bool enable)
 {
     RuntimeEnabledFeatures::setFileSystemEnabled(enable);
 }
 
@@ skipping 167 matching lines @@
 {
     RuntimeEnabledFeatures::setPreciseMemoryInfoEnabled(enable);
 }
 
 void WebRuntimeFeatures::enableLayerSquashing(bool enable)
 {
     RuntimeEnabledFeatures::setLayerSquashingEnabled(enable);
 }
 
 } // namespace blink