Oilpan: enable eager tracing of common animation objects.

Source/core/animation/Keyframe.h

 // Copyright 2014 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.
 
 #ifndef Keyframe_h
 #define Keyframe_h
 
 #include "core/CSSPropertyNames.h"
 #include "core/animation/AnimationEffect.h"
 #include "core/animation/AnimationNode.h"
@@ skipping 79 matching lines @@
         , m_composite(composite)
         , m_easing(easing)
     {
     }
 
     double m_offset;
     AnimationEffect::CompositeOperation m_composite;
     RefPtr<TimingFunction> m_easing;
 };
 
-}
+WILL_BE_EAGERLY_TRACED(Keyframe);
+WILL_BE_EAGERLY_TRACED(Keyframe::PropertySpecificKeyframe);
 
-#endif
+} // namespace blink
+
+#endif // Keyframe_h