Revert of Removed unused ScrollAnimatorMac methods.

Source/platform/mac/ScrollAnimatorMac.mm

Index: Source/platform/mac/ScrollAnimatorMac.mm
diff --git a/Source/platform/mac/ScrollAnimatorMac.mm b/Source/platform/mac/ScrollAnimatorMac.mm
index 8e4577287c9281addc5e034d9e6a201faaf0d465..6ab30748bb030c8766b1660684868531208ea12e 100644
--- a/Source/platform/mac/ScrollAnimatorMac.mm
+++ b/Source/platform/mac/ScrollAnimatorMac.mm
@@ -129,6 +129,13 @@
     return NSMakeRect(currentPosition.x(), currentPosition.y(), 0, 0);
 }
 
+- (void)_immediateScrollToPoint:(NSPoint)newPosition
+{
+    if (!_animator)
+        return;
+    _animator->immediateScrollToPointForScrollAnimation(newPosition);
+}
+
 - (NSPoint)_pixelAlignProposedScrollPosition:(NSPoint)newOrigin
 {
     return newOrigin;
@@ -762,6 +769,12 @@
     notifyPositionChanged();
 }
 
+void ScrollAnimatorMac::immediateScrollToPointForScrollAnimation(const FloatPoint& newPosition)
+{
+    ASSERT(m_scrollAnimationHelper);
+    immediateScrollTo(newPosition);
+}
+
 void ScrollAnimatorMac::contentAreaWillPaint() const
 {
     if (!scrollableArea()->scrollbarsCanBeActive())