Web Animations CSS: Fixing startDelay for compositor translation.

Source/core/animation/CompositorAnimations.cpp

 /*
  * 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 339 matching lines @@
     if (out.alternate && (skippedIterations % 2))
         out.reverse = !out.reverse;
 
     if (!std::isfinite(timing.iterationCount)) {
         out.adjustedIterationCount = -1;
     } else {
         out.adjustedIterationCount = std::floor(timing.iterationCount) - skippedIterations;
         ASSERT(out.adjustedIterationCount > 0);
     }
 
-    out.scaledTimeOffset = scaledStartDelay + skippedIterations * out.scaledDuration;
-    ASSERT(out.scaledTimeOffset <= 0);
+    // Compositor's time offset is positive for seeking into the animation.
+    out.scaledTimeOffset = -(scaledStartDelay + skippedIterations * out.scaledDuration);
+    ASSERT(out.scaledTimeOffset >= 0);
     return true;
 }
 
 namespace {
 
 template<typename PlatformAnimationKeyframeType>
 static PassOwnPtr<PlatformAnimationKeyframeType> createPlatformKeyframe(double offset, const AnimatableValue&)
 {
     // Only the specialized versions of this templated function (found in
     // the cpp file) should ever be called.
@@ skipping 175 matching lines @@
         animation->setIterations(compositorTiming.adjustedIterationCount);
         animation->setTimeOffset(compositorTiming.scaledTimeOffset);
         animation->setAlternatesDirection(compositorTiming.alternate);
 
         animations.append(animation.release());
     }
     ASSERT(!animations.isEmpty());
 }
 
 } // namespace WebCore