Revert of Remove StringBuilder::appendLiteral.

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

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/css/StyleRuleKeyframe.h"
 
 #include "core/css/StylePropertySet.h"
 #include "core/css/parser/CSSParser.h"
 #include "wtf/text/StringBuilder.h"
 
 namespace blink {
 
 StyleRuleKeyframe::StyleRuleKeyframe(PassOwnPtr<Vector<double>> keys, StylePropertySet* properties)
 : StyleRuleBase(Keyframe)
 , m_properties(properties)
 , m_keys(*keys)
 {
 }
 
 String StyleRuleKeyframe::keyText() const
 {
     ASSERT(!m_keys.isEmpty());
 
     StringBuilder keyText;
     for (unsigned i = 0; i < m_keys.size(); ++i) {
         if (i)
-            keyText.append(", ");
+            keyText.appendLiteral(", ");
         keyText.appendNumber(m_keys.at(i) * 100);
         keyText.append('%');
     }
 
     return keyText.toString();
 }
 
 bool StyleRuleKeyframe::setKeyText(const String& keyText)
 {
     ASSERT(!keyText.isNull());
@@ skipping 15 matching lines @@
 {
     if (!m_properties->isMutable())
         m_properties = m_properties->mutableCopy();
     return *toMutableStylePropertySet(m_properties.get());
 }
 
 String StyleRuleKeyframe::cssText() const
 {
     StringBuilder result;
     result.append(keyText());
-    result.append(" { ");
+    result.appendLiteral(" { ");
     String decls = m_properties->asText();
     result.append(decls);
     if (!decls.isEmpty())
         result.append(' ');
     result.append('}');
     return result.toString();
 }
 
 DEFINE_TRACE_AFTER_DISPATCH(StyleRuleKeyframe)
 {
     visitor->trace(m_properties);
     StyleRuleBase::traceAfterDispatch(visitor);
 }
 
 } // namespace blink