Oilpan: enable eager tracing of common animation objects.

Source/core/animation/Interpolation.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 Interpolation_h
 #define Interpolation_h
 
 #include "core/animation/InterpolableValue.h"
 #include "platform/heap/Handle.h"
 
@@ skipping 24 matching lines @@
 
     Interpolation(PassOwnPtrWillBeRawPtr<InterpolableValue> start, PassOwnPtrWillBeRawPtr<InterpolableValue> end);
 
 private:
     InterpolableValue* getCachedValueForTesting() const { return m_cachedValue.get(); }
 
     friend class AnimationInterpolableValueTest;
     friend class AnimationInterpolationEffectTest;
 };
 
-}
+WILL_BE_EAGERLY_TRACED(Interpolation);
 
-#endif
+} // namespace blink
+
+#endif // Interpolation_h