Web Animations: Timeline should not advance during task execution

Source/web/WebKit.cpp

Index: Source/web/WebKit.cpp
diff --git a/Source/web/WebKit.cpp b/Source/web/WebKit.cpp
index e2615483f845f2685a54a7c72ba93b39bec94f5d..371a507b376784b4bb3fd1b852c3c475b34c7eb6 100644
--- a/Source/web/WebKit.cpp
+++ b/Source/web/WebKit.cpp
@@ -35,6 +35,7 @@
 #include "bindings/v8/V8Binding.h"
 #include "bindings/v8/V8Initializer.h"
 #include "core/Init.h"
+#include "core/animation/AnimationClock.h"
 #include "core/dom/Microtask.h"
 #include "core/frame/Settings.h"
 #include "core/page/Page.h"
@@ -66,8 +67,11 @@ namespace {
 
 class EndOfTaskRunner : public WebThread::TaskObserver {
 public:
-    virtual void willProcessTask() { }
-    virtual void didProcessTask()
+    virtual void willProcessTask() OVERRIDE
+    {
+        WebCore::AnimationClock::notifyTaskStart();
+    }
+    virtual void didProcessTask() OVERRIDE
     {
         WebCore::Microtask::performCheckpoint();
     }