Revert of Remove StringBuilder::appendLiteral.

third_party/WebKit/Source/core/css/CSSGroupingRule.cpp

 /*
  * Copyright (C) 2011 Adobe Systems Incorporated. All rights reserved.
  * Copyright (C) 2012 Apple 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:
  *
  * 1. Redistributions of source code must retain the above
  *    copyright notice, this list of conditions and the following
@@ skipping 91 matching lines @@
 
     if (m_childRuleCSSOMWrappers[index])
         m_childRuleCSSOMWrappers[index]->setParentRule(0);
     m_childRuleCSSOMWrappers.remove(index);
 }
 
 void CSSGroupingRule::appendCSSTextForItems(StringBuilder& result) const
 {
     unsigned size = length();
     for (unsigned i = 0; i < size; ++i) {
-        result.append("  ");
+        result.appendLiteral("  ");
         result.append(item(i)->cssText());
         result.append('\n');
     }
 }
 
 unsigned CSSGroupingRule::length() const
 {
     return m_groupRule->childRules().size();
 }
 
@@ skipping 27 matching lines @@
 
 DEFINE_TRACE(CSSGroupingRule)
 {
     CSSRule::trace(visitor);
     visitor->trace(m_childRuleCSSOMWrappers);
     visitor->trace(m_groupRule);
     visitor->trace(m_ruleListCSSOMWrapper);
 }
 
 } // namespace blink