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

Source/core/css/CSSImageSetValue.cpp

 /*
  * 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 disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 131 matching lines @@
 
 String CSSImageSetValue::customCSSText() const
 {
     StringBuilder result;
     result.append("-webkit-image-set(");
 
     size_t length = this->length();
     size_t i = 0;
     while (i < length) {
         if (i > 0)
-            result.append(", ");
+            result.appendLiteral(", ");
 
         const CSSValue* imageValue = item(i);
         result.append(imageValue->cssText());
         result.append(' ');
 
         ++i;
         ASSERT_WITH_SECURITY_IMPLICATION(i < length);
         const CSSValue* scaleFactorValue = item(i);
         result.append(scaleFactorValue->cssText());
         // FIXME: Eventually the scale factor should contain it's own unit http://wkb.ug/100120.
         // For now 'x' is hard-coded in the parser, so we hard-code it here too.
         result.append('x');
 
         ++i;
     }
 
-    result.append(")");
+    result.append(')');
     return result.toString();
 }
 
 bool CSSImageSetValue::hasFailedOrCanceledSubresources() const
 {
     if (!m_imageSet || !m_imageSet->isImageResourceSet())
         return false;
     if (Resource* cachedResource = toStyleFetchedImageSet(m_imageSet)->cachedImage())
         return cachedResource->loadFailedOrCanceled();
     return true;
 }
 
 CSSImageSetValue::CSSImageSetValue(const CSSImageSetValue& cloneFrom)
     : CSSValueList(cloneFrom)
     , m_accessedBestFitImage(false)
     , m_scaleFactor(1)
 {
     // Non-CSSValueList data is not accessible through CSS OM, no need to clone.
 }
 
 PassRefPtrWillBeRawPtr<CSSImageSetValue> CSSImageSetValue::cloneForCSSOM() const
 {
     return adoptRefWillBeNoop(new CSSImageSetValue(*this));
 }
 
 } // namespace blink