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

Source/web/WebViewImpl.cpp

Index: Source/web/WebViewImpl.cpp
diff --git a/Source/web/WebViewImpl.cpp b/Source/web/WebViewImpl.cpp
index 5e21123d026f58b4ec1f0cfb3f5fde7051ac52ba..979a54dd8efe30cf60b7b1844cdc3f8a1b9e9274 100644
--- a/Source/web/WebViewImpl.cpp
+++ b/Source/web/WebViewImpl.cpp
@@ -4307,7 +4307,10 @@ void WebViewImpl::applyViewportDeltas(
 {
     ASSERT(pinchVirtualViewportEnabled());
 
-    if (!mainFrameImpl() || !mainFrameImpl()->frameView())
+    if (!mainFrameImpl())
+        return;
+    FrameView* frameView = mainFrameImpl()->frameView();
+    if (!frameView)
         return;
 
     setTopControlsContentOffset(m_topControlsContentOffset + topControlsDelta);
@@ -4319,6 +4322,8 @@ void WebViewImpl::applyViewportDeltas(
     if (pageScaleDelta != 1)
         m_doubleTapZoomPending = false;
 
+    frameView->setElasticOverscroll(elasticOverscrollDelta + frameView->elasticOverscroll());
+
     IntPoint mainFrameScrollOffset = IntPoint(mainFrame()->scrollOffset());
     mainFrameScrollOffset.move(mainFrameDelta.width, mainFrameDelta.height);
     updateMainFrameScrollPosition(mainFrameScrollOffset, false);