Use StringBuilder::appendLiteral() / StringBuilder::append(char) when possible

Source/core/css/CSSStyleRule.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * (C) 2002-2003 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2002, 2005, 2006, 2008, 2012 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 52 matching lines @@
         m_propertiesCSSOMWrapper = StyleRuleCSSStyleDeclaration::create(m_styleRule->mutableProperties(), const_cast<CSSStyleRule*>(this));
     }
     return m_propertiesCSSOMWrapper.get();
 }
 
 String CSSStyleRule::generateSelectorText() const
 {
     StringBuilder builder;
     for (const CSSSelector* selector = m_styleRule->selectorList().first(); selector; selector = CSSSelectorList::next(*selector)) {
         if (selector != m_styleRule->selectorList().first())
-            builder.append(", ");
+            builder.appendLiteral(", ");
         builder.append(selector->selectorText());
     }
     return builder.toString();
 }
 
 String CSSStyleRule::selectorText() const
 {
     if (hasCachedSelectorText()) {
         ASSERT(selectorTextCache().contains(this));
         return selectorTextCache().get(this);
@@ skipping 47 matching lines @@
 }
 
 void CSSStyleRule::trace(Visitor* visitor)
 {
     visitor->trace(m_styleRule);
     visitor->trace(m_propertiesCSSOMWrapper);
     CSSRule::trace(visitor);
 }
 
 } // namespace blink