Reduce rectangle merges when doing region-based hit test on text boxes

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 858 matching lines @@
 }
 
 namespace {
 
 class HitTestCulledInlinesGeneratorContext {
  public:
   HitTestCulledInlinesGeneratorContext(Region& region,
                                        const HitTestLocation& location)
       : m_intersected(false), m_region(region), m_location(location) {}
   void operator()(const FloatRect& rect) {
-    m_intersected = m_intersected || m_location.intersects(rect);
-    m_region.unite(enclosingIntRect(rect));
+    bool intersects = m_location.intersects(rect);
+    m_intersected = m_intersected || intersects;

[wkorman, 2017/01/04 00:36:35]

nit: could use |= here and below.

+    if (intersects)
+      m_region.unite(enclosingIntRect(rect));
   }
   void operator()(const LayoutRect& rect) {
-    m_intersected = m_intersected || m_location.intersects(rect);
-    m_region.unite(enclosingIntRect(rect));
+    bool intersects = m_location.intersects(rect);
+    m_intersected = m_intersected || intersects;
+    if (intersects)
+      m_region.unite(enclosingIntRect(rect));
   }
   bool intersected() const { return m_intersected; }
 
  private:
   bool m_intersected;
   Region& m_region;
   const HitTestLocation& m_location;
 };
 
 }  // unnamed namespace
@@ skipping 619 matching lines @@
     paintInvalidator.invalidateDisplayItemClient(*box, invalidationReason);
 }
 
 // TODO(lunalu): Not to just dump 0, 0 as the x and y here
 LayoutRect LayoutInline::debugRect() const {
   IntRect linesBox = enclosingIntRect(linesBoundingBox());
   return LayoutRect(IntRect(0, 0, linesBox.width(), linesBox.height()));
 }
 
 }  // namespace blink