[Oilpan] Migrate most classes under core/animations to Oilpan heap.

Source/core/animation/animatable/AnimatableLengthBox.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 15 matching lines @@
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "core/animation/animatable/AnimatableLengthBox.h"
 
 namespace blink {
 
-PassRefPtrWillBeRawPtr<AnimatableValue> AnimatableLengthBox::interpolateTo(const AnimatableValue* value, double fraction) const
+AnimatableValue* AnimatableLengthBox::interpolateTo(const AnimatableValue* value, double fraction) const
 {
     const AnimatableLengthBox* lengthBox = toAnimatableLengthBox(value);
     return AnimatableLengthBox::create(
         AnimatableValue::interpolate(this->left(), lengthBox->left(), fraction),
         AnimatableValue::interpolate(this->right(), lengthBox->right(), fraction),
         AnimatableValue::interpolate(this->top(), lengthBox->top(), fraction),
         AnimatableValue::interpolate(this->bottom(), lengthBox->bottom(), fraction));
 }
 
 bool AnimatableLengthBox::equalTo(const AnimatableValue* value) const
 {
     const AnimatableLengthBox* lengthBox = toAnimatableLengthBox(value);
     return left()->equals(lengthBox->left())
         && right()->equals(lengthBox->right())
         && top()->equals(lengthBox->top())
         && bottom()->equals(lengthBox->bottom());
 }
 
 DEFINE_TRACE(AnimatableLengthBox)
 {
     visitor->trace(m_left);
     visitor->trace(m_right);
     visitor->trace(m_top);
     visitor->trace(m_bottom);
     AnimatableValue::trace(visitor);
 }
 
 }