Revert of Remove PaintInfo's paintingRoot

third_party/WebKit/Source/core/paint/PaintInfo.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/PaintInfo.h"
 
 namespace blink {
 
+void PaintInfo::updatePaintingRootForChildren(const LayoutObject* layoutObject)
+{
+    if (!paintingRoot)
+        return;
+
+    // If we're the painting root, kids draw normally, and see root of nullptr.
+    if (paintingRoot == layoutObject) {
+        paintingRoot = nullptr;
+        return;
+    }
+}
+
+bool PaintInfo::shouldPaintWithinRoot(const LayoutObject* layoutObject) const
+{
+    return !paintingRoot || paintingRoot == layoutObject;
+}
+
 void PaintInfo::updateCullRect(const AffineTransform& localToParentTransform)
 {
     m_cullRect.updateCullRect(localToParentTransform);
 }
 
 } // namespace blink