Allow Web Animations flags to be turned off as well as on

public/web/WebRuntimeFeatures.h

Index: public/web/WebRuntimeFeatures.h
diff --git a/public/web/WebRuntimeFeatures.h b/public/web/WebRuntimeFeatures.h
index bf7314ddd9bafa44038332cb060f5681b9f972c5..d49d3d65639db77ae2311bcda303c329a35c8b84 100644
--- a/public/web/WebRuntimeFeatures.h
+++ b/public/web/WebRuntimeFeatures.h
@@ -131,8 +131,11 @@ public:
     BLINK_EXPORT static void enableTouch(bool);
     BLINK_EXPORT static bool isTouchEnabled();
 
-    BLINK_EXPORT static void enableWebAnimationsCSS();
-    BLINK_EXPORT static void enableWebAnimationsSVG();
+    // FIXME: Default values are a temporary measure until the addition of an
+    // 'enable' parameter here is rolled into Chromium and runtime_features.cc
+    // is updated.
+    BLINK_EXPORT static void enableWebAnimationsCSS(bool enable = true);
+    BLINK_EXPORT static void enableWebAnimationsSVG(bool enable = true);
 
     BLINK_EXPORT static void enableWebAudio(bool);
     BLINK_EXPORT static bool isWebAudioEnabled();