C++11: Replace 0 with nullptr where applicable in layout code.

Source/core/layout/LayoutTextControl.cpp

 /**
  * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
  *           (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 187 matching lines @@
     "#PilGi",
 };
 
 // For font families where any of the fonts don't have a valid entry in the OS/2 table
 // for avgCharWidth, fallback to the legacy webkit behavior of getting the avgCharWidth
 // from the width of a '0'. This only seems to apply to a fixed number of Mac fonts,
 // but, in order to get similar rendering across platforms, we do this check for
 // all platforms.
 bool LayoutTextControl::hasValidAvgCharWidth(AtomicString family)
 {
-    static HashSet<AtomicString>* fontFamiliesWithInvalidCharWidthMap = 0;
+    static HashSet<AtomicString>* fontFamiliesWithInvalidCharWidthMap = nullptr;
 
     if (family.isEmpty())
         return false;
 
     if (!fontFamiliesWithInvalidCharWidthMap) {
         fontFamiliesWithInvalidCharWidthMap = new HashSet<AtomicString>;
 
         for (size_t i = 0; i < WTF_ARRAY_LENGTH(fontFamiliesWithInvalidCharWidth); ++i)
             fontFamiliesWithInvalidCharWidthMap->add(AtomicString(fontFamiliesWithInvalidCharWidth[i]));
     }
@@ skipping 64 matching lines @@
 
 void LayoutTextControl::addFocusRingRects(Vector<LayoutRect>& rects, const LayoutPoint& additionalOffset) const
 {
     if (!size().isEmpty())
         rects.append(LayoutRect(additionalOffset, size()));
 }
 
 LayoutObject* LayoutTextControl::layoutSpecialExcludedChild(bool relayoutChildren, SubtreeLayoutScope& layoutScope)
 {
     HTMLElement* placeholder = toHTMLTextFormControlElement(node())->placeholderElement();
-    LayoutObject* placeholderLayoutObject = placeholder ? placeholder->layoutObject() : 0;
+    LayoutObject* placeholderLayoutObject = placeholder ? placeholder->layoutObject() : nullptr;
     if (!placeholderLayoutObject)
-        return 0;
+        return nullptr;
     if (relayoutChildren)
         layoutScope.setChildNeedsLayout(placeholderLayoutObject);
     return placeholderLayoutObject;
 }
 
 } // namespace blink