Remove special wheel handling path from ScrollableArea

Source/platform/scroll/ScrollAnimatorNone.cpp

Index: Source/platform/scroll/ScrollAnimatorNone.cpp
diff --git a/Source/platform/scroll/ScrollAnimatorNone.cpp b/Source/platform/scroll/ScrollAnimatorNone.cpp
index 8c0df06c739c5a19ceb245d0db9040bb35404d5f..5aa4e199845f54d94b2da15189e863f0e60c6850 100644
--- a/Source/platform/scroll/ScrollAnimatorNone.cpp
+++ b/Source/platform/scroll/ScrollAnimatorNone.cpp
@@ -424,13 +424,14 @@ ScrollResultOneDimensional ScrollAnimatorNone::userScroll(ScrollbarOrientation o
 
     PerAxisData& data = (orientation == VerticalScrollbar) ? m_verticalData : m_horizontalData;
     bool needToScroll = data.updateDataFromParameters(step, delta, scrollableSize, WTF::monotonicallyIncreasingTime(), &parameters);
+    float unusedDelta = needToScroll ? delta - (data.m_desiredPosition - *data.m_currentPosition) : delta;
     if (needToScroll && !animationTimerActive()) {
         m_startTime = data.m_startTime;
         animationWillStart();
         animationTimerFired();
         scrollableArea()->registerForAnimation();
     }
-    return ScrollResultOneDimensional(needToScroll);
+    return ScrollResultOneDimensional(needToScroll, unusedDelta);

[bokan, 2015/08/19 12:42:47]

This wasn't returning unused delta. It's needed for overscroll to work
correctly.

[Rick Byers, 2015/08/19 17:33:31]

So you're fixing a bug here?  Add a test for it?

[bokan, 2015/08/19 18:45:47]

This is caught by
WebFrameOverscrollTest.ReportingLatestOverscrollForElasticOverscroll, it was
uncovered by this refactoring because we no longer use a special path for the
RootFrame.

[Rick Byers, 2015/08/19 19:42:09]

Ah, ok - thanks.

 }
 
 void ScrollAnimatorNone::scrollToOffsetWithoutAnimation(const FloatPoint& offset)