Mac: Update scrollbar size and input position during impl-overscroll

Source/web/WebInputEventConversion.cpp

 /*
  * Copyright (C) 2009 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 53 matching lines @@
 static FloatSize scaleSizeToWindow(const Widget* widget, FloatSize size)
 {
     return FloatSize(scaleDeltaToWindow(widget, size.width()), scaleDeltaToWindow(widget, size.height()));
 }
 
 static FloatPoint convertHitPointToWindow(const Widget* widget, FloatPoint point)
 {
     float scale = 1;
     IntSize offset;
     IntPoint pinchViewport;
+    FloatSize overscrollOffset;
     if (widget) {
         FrameView* rootView = toFrameView(widget->root());
         if (rootView) {
             scale = rootView->inputEventsScaleFactor();
             offset = rootView->inputEventsOffsetForEmulation();
             pinchViewport = flooredIntPoint(rootView->page()->frameHost().pinchViewport().visibleRect().location());
+            overscrollOffset = rootView->elasticOverscroll();
         }
     }
     return FloatPoint(
-        (point.x() - offset.width()) / scale + pinchViewport.x(),
-        (point.y() - offset.height()) / scale + pinchViewport.y());
+        (point.x() - offset.width()) / scale + pinchViewport.x() + overscrollOffset.width(),
+        (point.y() - offset.height()) / scale + pinchViewport.y() + overscrollOffset.height());
 }
 
 static int toWebEventModifiers(unsigned platformModifiers)
 {
     int newModifiers = 0;
     if (platformModifiers & PlatformEvent::ShiftKey)
         newModifiers |= WebInputEvent::ShiftKey;
     if (platformModifiers & PlatformEvent::CtrlKey)
         newModifiers |= WebInputEvent::ControlKey;
     if (platformModifiers & PlatformEvent::AltKey)
@@ skipping 707 matching lines @@
     modifiers = getWebInputModifiers(event);
 
     globalX = event.screenX();
     globalY = event.screenY();
     IntPoint localPoint = convertAbsoluteLocationForRenderObject(event.absoluteLocation(), *renderObject);
     x = localPoint.x();
     y = localPoint.y();
 }
 
 } // namespace blink