Implement CSSOM smooth scroll for Elements

Source/platform/scroll/ProgrammaticScrollAnimator.cpp

 // 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.
 
 #include "config.h"
 #include "platform/scroll/ProgrammaticScrollAnimator.h"
 
 #include "platform/geometry/IntPoint.h"
 #include "platform/scroll/ScrollableArea.h"
 #include "public/platform/Platform.h"
@@ skipping 23 matching lines @@
     m_startTime = 0.0;
 }
 
 void ProgrammaticScrollAnimator::animateToOffset(FloatPoint offset)
 {
     m_startTime = 0.0;
     m_targetOffset = offset;
     m_animationCurve = adoptPtr(Platform::current()->compositorSupport()->createScrollOffsetAnimationCurve(m_targetOffset, WebCompositorAnimationCurve::TimingFunctionTypeEaseInOut));
 
     m_animationCurve->setInitialValue(FloatPoint(m_scrollableArea->scrollPosition()));
+    m_scrollableArea->registerForAnimation();
     if (!m_scrollableArea->scheduleAnimation()) {
         resetAnimationState();
         m_scrollableArea->notifyScrollPositionChanged(IntPoint(offset.x(), offset.y()));
     }
 }
 
 void ProgrammaticScrollAnimator::cancelAnimation()
 {
     resetAnimationState();
 }
@@ skipping 10 matching lines @@
 
         if (isFinished) {
             resetAnimationState();
         } else if (!m_scrollableArea->scheduleAnimation()) {
             m_scrollableArea->notifyScrollPositionChanged(IntPoint(m_targetOffset.x(), m_targetOffset.y()));
             resetAnimationState();
         }
     }
 }
 
+bool ProgrammaticScrollAnimator::hasRunningAnimation() const
+{
+    return !!m_animationCurve;
+}
+
 } // namespace blink