Recompute slow scroll regions after overflow recalc

Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 624 matching lines @@
 
 void FrameView::recalcOverflowAfterStyleChange()
 {
     LayoutView* layoutView = this->layoutView();
     RELEASE_ASSERT(layoutView);
     if (!layoutView->needsOverflowRecalcAfterStyleChange())
         return;
 
     layoutView->recalcOverflowAfterStyleChange();
 
+    // Changing overflow should notify scrolling coordinator to ensures that it
+    // updates non-fast scroll rects even if there is no layout.
+    if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())
+        scrollingCoordinator->notifyOverflowUpdated();
+
     IntRect documentRect = layoutView->documentRect();
     if (scrollOrigin() == -documentRect.location() && contentsSize() == documentRect.size())
         return;
 
     if (needsLayout())
         return;
 
     InUpdateScrollbarsScope inUpdateScrollbarsScope(this);
 
     bool shouldHaveHorizontalScrollbar = false;
@@ skipping 3323 matching lines @@
 
     if (!graphicsLayer)
         return;
 
     DeprecatedPaintLayer::mapRectToPaintInvalidationBacking(localFrame->contentLayoutObject(), paintInvalidationContainer, viewRect);
 
     graphicsLayerTimingRequests.add(graphicsLayer, Vector<std::pair<int64_t, WebRect>>()).storedValue->value.append(std::make_pair(m_frame->frameID(), enclosingIntRect(viewRect)));
 }
 
 } // namespace blink