Revert of Web Animations: Timeline should not advance during task execution

Source/core/animation/AnimationClock.cpp

 /*
  * Copyright (c) 2014, 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 13 matching lines @@
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "core/animation/AnimationClock.h"
 
-#include "wtf/CurrentTime.h"
-#include <math.h>
-
-namespace {
-
-// FIXME: This is an approximation of time between frames, used when
-// ticking the animation clock outside of animation frame callbacks.
-// Ideally this would be generated by the compositor.
-const double approximateFrameTime = 1 / 60.0;
-
-}
-
 namespace WebCore {
 
-unsigned AnimationClock::s_currentTask = 0;
-
 void AnimationClock::updateTime(double time)
 {
     if (time > m_time)
         m_time = time;
-    m_currentTask = s_currentTask;
+    m_frozen = true;
 }
 
 double AnimationClock::currentTime()
 {
-    if (m_currentTask != s_currentTask) {
-        const double currentTime = m_monotonicallyIncreasingTime();
-        if (m_time < currentTime) {
-            // Advance to the first estimated frame after the current time.
-            const double frameShift = fmod(currentTime - m_time, approximateFrameTime);
-            const double newTime = currentTime + approximateFrameTime - frameShift;
-            ASSERT(newTime > currentTime);
-            ASSERT(newTime <= currentTime + approximateFrameTime);
-            updateTime(newTime);
-        } else {
-            m_currentTask = s_currentTask;
-        }
+    if (!m_frozen) {
+        double newTime = m_monotonicallyIncreasingTime();
+        if (newTime >= m_time + minTimeBeforeUnsynchronizedAnimationClockTick)
+            m_time = newTime;
     }
     return m_time;
 }
 
-void AnimationClock::resetTimeForTesting()
-{
-    m_time = 0;
-    m_currentTask = 0;
-    s_currentTask = 0;
 }
-
-}