Ensure baseComputedStyle optimisation is cleared during registered custom property animations

third_party/WebKit/Source/core/animation/AnimationClock.h

 /*
  * 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 39 matching lines @@
  public:
   explicit AnimationClock(WTF::TimeFunction monotonicallyIncreasingTime =
                               WTF::monotonicallyIncreasingTime)
       : m_monotonicallyIncreasingTime(monotonicallyIncreasingTime),
         m_time(0),
         m_taskForWhichTimeWasCalculated(std::numeric_limits<unsigned>::max()) {}
 
   void updateTime(double time);
   double currentTime();
   void resetTimeForTesting(double time = 0);
+  void disableSyntheticTimeForTesting() {
+    m_monotonicallyIncreasingTime = nullptr;
+  }
 
   // notifyTaskStart should be called right before the main message loop starts
   // to run the next task from the message queue.
   static void notifyTaskStart() { ++s_currentlyRunningTask; }
 
  private:
   WTF::TimeFunction m_monotonicallyIncreasingTime;
   double m_time;
   unsigned m_taskForWhichTimeWasCalculated;
   static unsigned s_currentlyRunningTask;
 };
 
 }  // namespace blink
 
 #endif  // AnimationClock_h