Gracefully handle zero duration curves in CCActiveAnimation

cc/CCActiveAnimation.cpp

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 
 #include "CCActiveAnimation.h"
 
 #include "CCAnimationCurve.h"
 #include "TraceEvent.h"
@@ skipping 136 matching lines @@
     trimmed -= m_startTime + m_totalPausedTime;
 
     // Zero is always the start of the animation.
     if (trimmed <= 0)
         return 0;
 
     // Always return zero if we have no iterations.
     if (!m_iterations)
         return 0;
 
+    // Don't attempt to trim if we have no duration.
+    if (m_curve->duration() <= 0)
+        return 0;
+
     // If less than an iteration duration, just return trimmed.
     if (trimmed < m_curve->duration())
         return trimmed;
 
     // If greater than or equal to the total duration, return iteration duration.
     if (m_iterations >= 0 && trimmed >= m_curve->duration() * m_iterations) {
         if (m_alternatesDirection && !(m_iterations % 2))
             return 0;
         return m_curve->duration();
     }
@@ skipping 34 matching lines @@
 {
     // Currently, we only push changes due to pausing and resuming animations on the main thread.
     if (m_runState == CCActiveAnimation::Paused || other->m_runState == CCActiveAnimation::Paused) {
         other->m_runState = m_runState;
         other->m_pauseTime = m_pauseTime;
         other->m_totalPausedTime = m_totalPausedTime;
     }
 }
 
 } // namespace cc