Add option to force document level passive event listeners as a runtime feature.

third_party/WebKit/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 182 matching lines @@
 void WebRuntimeFeatures::enablePagePopup(bool enable)
 {
     RuntimeEnabledFeatures::setPagePopupEnabled(enable);
 }
 
 void WebRuntimeFeatures::enableParseHTMLOnMainThread(bool enable)
 {
     RuntimeEnabledFeatures::setParseHTMLOnMainThreadEnabled(enable);
 }
 
+void WebRuntimeFeatures::enablePassiveDocumentEventListeners(bool enable)
+{
+    RuntimeEnabledFeatures::setPassiveDocumentEventListenersEnabled(enable);
+}
+
 void WebRuntimeFeatures::enablePermissionsAPI(bool enable)
 {
     RuntimeEnabledFeatures::setPermissionsEnabled(enable);
 }
 
 void WebRuntimeFeatures::enablePointerEvent(bool enable)
 {
     RuntimeEnabledFeatures::setPointerEventEnabled(enable);
 }
 
@@ skipping 116 matching lines @@
 {
     RuntimeEnabledFeatures::setScrollAnchoringEnabled(enable);
 }
 
 void WebRuntimeFeatures::enableAutoplayMutedVideos(bool enable)
 {
     RuntimeEnabledFeatures::setAutoplayMutedVideosEnabled(enable);
 }
 
 } // namespace blink