Use the bounding box of all descendants for localVisualRect if there is a mask.

third_party/WebKit/Source/core/layout/LayoutBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc.
  *               All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 2229 matching lines @@
       return false;
   }
 
   return true;
 }
 
 LayoutRect LayoutBox::localVisualRect() const {
   if (style()->visibility() != EVisibility::Visible)
     return LayoutRect();
 
+  if (hasMask() && !RuntimeEnabledFeatures::slimmingPaintV2Enabled())
+    return LayoutRect(layer()->boxForFilterOrMask());
   return selfVisualOverflowRect();
 }
 
 void LayoutBox::inflateVisualRectForFilterUnderContainer(
     LayoutRect& rect,
     const LayoutObject& container,
     const LayoutBoxModelObject* ancestorToStopAt) const {
   // Apply visual overflow caused by reflections and filters defined on objects
   // between this object and container (not included) or ancestorToStopAt
   // (included).
@@ skipping 3356 matching lines @@
   LayoutRect rect = frameRect();
 
   LayoutBlock* block = containingBlock();
   if (block)
     block->adjustChildDebugRect(rect);
 
   return rect;
 }
 
 }  // namespace blink