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

Source/core/css/CSSSelectorList.cpp

 /*
  * Copyright (C) 2008, 2012 Apple Inc. All rights reserved.
  * 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 96 matching lines @@
 
     fastFree(m_selectorArray);
 }
 
 String CSSSelectorList::selectorsText() const
 {
     StringBuilder result;
 
     for (const CSSSelector* s = first(); s; s = next(*s)) {
         if (s != first())
-            result.append(", ");
+            result.appendLiteral(", ");
         result.append(s->selectorText());
     }
 
     return result.toString();
 }
 
 template <typename Functor>
 static bool forEachTagSelector(Functor& functor, const CSSSelector& selector)
 {
     for (const CSSSelector* current = &selector; current; current = current->tagHistory()) {
@@ skipping 61 matching lines @@
     }
 };
 
 bool CSSSelectorList::selectorCrossesTreeScopes(size_t index) const
 {
     SelectorCrossesTreeScopes functor;
     return forEachTagSelector(functor, selectorAt(index));
 }
 
 } // namespace blink