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

Source/core/layout/LayoutRubyBase.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 19 matching lines @@
 
 #include "config.h"
 
 #include "core/layout/LayoutRubyBase.h"
 
 #include "core/layout/LayoutRubyRun.h"
 
 namespace blink {
 
 LayoutRubyBase::LayoutRubyBase()
-    : LayoutBlockFlow(0)
+    : LayoutBlockFlow(nullptr)
 {
     setInline(false);
 }
 
 LayoutRubyBase::~LayoutRubyBase()
 {
 }
 
 LayoutRubyBase* LayoutRubyBase::createAnonymous(Document* document)
 {
@@ skipping 90 matching lines @@
         return;
 
     // Inset the ruby base by half the inter-ideograph expansion amount.
     LayoutUnit inset = (logicalWidth - maxPreferredLogicalWidth) / (expansionOpportunityCount + 1);
 
     logicalLeft += inset / 2;
     logicalWidth -= inset;
 }
 
 } // namespace blink