Refactor LayoutInline::addOutlineRects to avoid tricky logic to avoid dups

Source/core/layout/LayoutBoxModelObject.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 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 396 matching lines @@
             }
         }
         return;
     }
 
     if (descendant.isBox()) {
         descendant.addOutlineRects(rects, additionalOffset + toLayoutBox(descendant).locationOffset());
         return;
     }
 
+    if (descendant.isLayoutInline()) {
+        // As an optimization, an ancestor has added rects for its line boxes covering descendants'
+        // line boxes, so descendants don't need to add line boxes again. For example, if the parent
+        // is a LayoutBlock, it adds rects for its RootOutlineBoxes which cover the line boxes of
+        // this LayoutInline. So the LayoutInline needs to add rects for children and continuations only.
+        toLayoutInline(descendant).addOutlineRectsForChildrenAndContinuations(rects, additionalOffset);
+        return;
+    }
+
     descendant.addOutlineRects(rects, additionalOffset);
 }
 
 bool LayoutBoxModelObject::calculateHasBoxDecorations() const
 {
     const ComputedStyle& styleToUse = styleRef();
     return hasBackground() || styleToUse.hasBorderDecoration() || styleToUse.hasAppearance() || styleToUse.boxShadow();
 }
 
 bool LayoutBoxModelObject::hasNonEmptyLayoutSize() const
@@ skipping 576 matching lines @@
     if (rootElementStyle->hasBackground())
         return false;
 
     if (node() != document().firstBodyElement())
         return false;
 
     return true;
 }
 
 } // namespace blink