Blink CompositorAnimations: Do not crash if no compositor animation player.

third_party/WebKit/Source/core/animation/CompositorAnimations.cpp

Index: third_party/WebKit/Source/core/animation/CompositorAnimations.cpp
diff --git a/third_party/WebKit/Source/core/animation/CompositorAnimations.cpp b/third_party/WebKit/Source/core/animation/CompositorAnimations.cpp
index 9d1a14131ead353d7f27b1d83a21592a746ff863..a74040611752e27cd465d8cf0c79d7d06ff67160 100644
--- a/third_party/WebKit/Source/core/animation/CompositorAnimations.cpp
+++ b/third_party/WebKit/Source/core/animation/CompositorAnimations.cpp
@@ -383,8 +383,8 @@ void CompositorAnimations::cancelAnimationOnCompositor(const Element& element, c
     }
     if (RuntimeEnabledFeatures::compositorAnimationTimelinesEnabled()) {
         WebCompositorAnimationPlayer* compositorPlayer = animation.compositorPlayer();
-        ASSERT(compositorPlayer);
-        compositorPlayer->removeAnimation(id);
+        if (compositorPlayer)
+            compositorPlayer->removeAnimation(id);
     } else {
         toLayoutBoxModelObject(element.layoutObject())->layer()->compositedLayerMapping()->mainGraphicsLayer()->removeAnimation(id);
     }