Use the single char overload of append() when possible.

third_party/WebKit/Source/platform/text/DateTimeFormatTest.cpp

 /*
  * Copyright (C) 2012 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
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 129 matching lines @@
         {
             return m_tokens == other.m_tokens;
         }
 
         String toString() const
         {
             StringBuilder builder;
             builder.append("Tokens(");
             for (unsigned index = 0; index < m_tokens.size(); ++index) {
                 if (index)
-                    builder.append(",");
+                    builder.append(',');
                 builder.append(m_tokens[index].toString());
             }
-            builder.append(")");
+            builder.append(')');
             return builder.toString();
         }
 
     private:
         Vector<Token> m_tokens;
     };
 
 protected:
     Tokens parse(const String& formatString)
     {
@@ skipping 162 matching lines @@
     EXPECT_EQ(DateTimeFormat::FieldTypeInvalid, single('O'));
     EXPECT_EQ(DateTimeFormat::FieldTypeInvalid, single('P'));
     EXPECT_EQ(DateTimeFormat::FieldTypeInvalid, single('R'));
     EXPECT_EQ(DateTimeFormat::FieldTypeInvalid, single('T'));
     EXPECT_EQ(DateTimeFormat::FieldTypeInvalid, single('U'));
     EXPECT_EQ(DateTimeFormat::FieldTypeInvalid, single('V'));
     EXPECT_EQ(DateTimeFormat::FieldTypeInvalid, single('X'));
 }
 
 } // namespace blink