Fix page jumping back to initial position after an overflow-bounce scroll.

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 1fbbb9f7b39d09c32d2d51c6e3b30c1d09919ad6..7789e447be714f4297bf0cd6c66ff4e1a24d9c70 100644
--- a/Source/platform/mac/ScrollAnimatorMac.mm
+++ b/Source/platform/mac/ScrollAnimatorMac.mm
@@ -693,6 +693,18 @@ FloatPoint ScrollAnimatorMac::adjustScrollPositionIfNecessary(const FloatPoint&
     return FloatPoint(newX, newY);
 }
 
+void ScrollAnimatorMac::adjustScrollPositionToBoundsIfNecessary()
+{
+    bool currentlyConstrainsToContentEdge = m_scrollableArea->constrainsScrollingToContentEdge();
+    m_scrollableArea->setConstrainsScrollingToContentEdge(true);
+
+    IntPoint currentScrollPosition = absoluteScrollPosition();
+    FloatPoint nearestPointWithinBounds = adjustScrollPositionIfNecessary(absoluteScrollPosition());
+    immediateScrollBy(nearestPointWithinBounds - currentScrollPosition);
+
+    m_scrollableArea->setConstrainsScrollingToContentEdge(currentlyConstrainsToContentEdge);
+}
+
 void ScrollAnimatorMac::immediateScrollTo(const FloatPoint& newPosition)
 {
     FloatPoint adjustedPosition = adjustScrollPositionIfNecessary(newPosition);