Revert of Web Animations: Remove AnimationPlayer discarding logic

Source/core/animation/AnimationPlayer.cpp

Index: Source/core/animation/AnimationPlayer.cpp
diff --git a/Source/core/animation/AnimationPlayer.cpp b/Source/core/animation/AnimationPlayer.cpp
index 95f732adde6e931d15faee04bfff7ea094c642c4..64c06896e306042b7529338806bdc05ad31e14c5 100644
--- a/Source/core/animation/AnimationPlayer.cpp
+++ b/Source/core/animation/AnimationPlayer.cpp
@@ -899,6 +899,15 @@
         InspectorInstrumentation::didCreateAnimationPlayer(m_player->timeline()->document(), *m_player);
 }
 
+
+#if !ENABLE(OILPAN)
+bool AnimationPlayer::canFree() const
+{
+    ASSERT(m_content);
+    return hasOneRef() && m_content->isAnimation() && m_content->hasOneRef();
+}
+#endif
+
 bool AnimationPlayer::addEventListener(const AtomicString& eventType, PassRefPtr<EventListener> listener, bool useCapture)
 {
     if (eventType == EventTypeNames::finish)