Change WebLayer::addAnimation to transfer ownership of WebAnimation.

Source/web/LinkHighlight.cpp

Index: Source/web/LinkHighlight.cpp
diff --git a/Source/web/LinkHighlight.cpp b/Source/web/LinkHighlight.cpp
index a42601978dd2ad3539e70f80e80ffbf5fe126755..add75010e14510b4e3301709da927465cd6e19f6 100644
--- a/Source/web/LinkHighlight.cpp
+++ b/Source/web/LinkHighlight.cpp
@@ -271,10 +271,14 @@ void LinkHighlight::startHighlightAnimationIfNeeded()
     // For layout tests we don't fade out.
     curve->add(WebFloatKeyframe(fadeDuration + extraDurationRequired, WebKit::layoutTestMode() ? startOpacity : 0));
 
-    m_animation = adoptPtr(compositorSupport->createAnimation(*curve, WebAnimation::TargetPropertyOpacity));
+    OwnPtr<WebAnimation> animation = adoptPtr(compositorSupport->createAnimation(*curve, WebAnimation::TargetPropertyOpacity));
 
     m_contentLayer->layer()->setDrawsContent(true);
-    m_contentLayer->layer()->addAnimation(m_animation.get());
+#if defined(ANIMATION_OWNERSHIP_NOT_TRANSFER)
+    m_contentLayer->layer()->addAnimation(animation.get());
+#else
+    m_contentLayer->layer()->addAnimation(animation.leakPtr());
+#endif
 
     invalidate();
     m_owningWebViewImpl->scheduleAnimation();