Add a runtime flag in WebRuntimeFeatures to enable 'image/webp' accept header

Source/bindings/v8/RuntimeEnabledFeatures.h

 /*
  * Copyright (C) 2009 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 230 matching lines @@
     static bool seamlessIFramesEnabled() { return areSeamlessIFramesEnabled; }
     static void setSeamlessIFramesEnabled(bool isEnabled) { areSeamlessIFramesEnabled = isEnabled; }
 
     static bool langAttributeAwareFormControlUIEnabled() { return isLangAttributeAwareFormControlUIEnabled; }
     // The lang attribute support is incomplete and should only be turned on for tests.
     static void setLangAttributeAwareFormControlUIEnabled(bool isEnabled) { isLangAttributeAwareFormControlUIEnabled = isEnabled; }
 
     static bool requestAutocompleteEnabled() { return isRequestAutocompleteEnabled; }
     static void setRequestAutocompleteEnabled(bool isEnabled) { isRequestAutocompleteEnabled = isEnabled; }
 
+#if USE(WEBP)
+    static void setWebPInAcceptHeaderEnabled(bool isEnabled) { isWebPInAcceptHeaderEnabled = isEnabled; }
+    static bool webPInAcceptHeaderEnabled() { return isWebPInAcceptHeaderEnabled; }
+#endif
+
 private:
     // Never instantiate.
     RuntimeEnabledFeatures() { }
 
     static bool isLocalStorageEnabled;
     static bool isSessionStorageEnabled;
     static bool isWebkitNotificationsEnabled;
     static bool isApplicationCacheEnabled;
     static bool isDataTransferItemsEnabled;
     static bool isGeolocationEnabled;
@@ skipping 65 matching lines @@
     static bool areExperimentalContentSecurityPolicyFeaturesEnabled;
 
     static bool areSeamlessIFramesEnabled;
 
 #if ENABLE(FONT_LOAD_EVENTS)
     static bool isFontLoadEventsEnabled;
 #endif
 
     static bool isDoNotTrackEnabled;
 
+#if USE(WEBP)
+    static bool isWebPInAcceptHeaderEnabled;
+#endif
+
 };
 
 } // namespace WebCore
 
 #endif // RuntimeEnabledFeatures_h