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

third_party/WebKit/Source/web/tests/FrameSerializerTest.cpp

 /*
  * Copyright (c) 2013, Opera Software ASA. 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 165 matching lines @@
                 completeURL = element.document().completeURL(attribute.value());
                 break;
             }
         }
 
         if (completeURL.isNull() || !m_rewriteURLs.contains(completeURL))
             return false;
 
         StringBuilder uriBuilder;
         uriBuilder.append(m_rewriteFolder);
-        uriBuilder.append("/");
+        uriBuilder.append('/');
         uriBuilder.append(m_rewriteURLs.get(completeURL));
         rewrittenLink = uriBuilder.toString();
         return true;
     }
 
     FrameTestHelpers::WebViewHelper m_helper;
     WebString m_folder;
     KURL m_baseUrl;
     Vector<SerializedResource> m_resources;
     HashMap<String, String> m_rewriteURLs;
@@ skipping 328 matching lines @@
     EXPECT_EQ("saved from url=(0015)http://foo.com/", FrameSerializer::markOfTheWebDeclaration(KURL(ParsedURLString, "http://foo.com")));
     EXPECT_EQ("saved from url=(0015)http://f-o.com/", FrameSerializer::markOfTheWebDeclaration(KURL(ParsedURLString, "http://f-o.com")));
     EXPECT_EQ("saved from url=(0019)http://foo.com-%2D/", FrameSerializer::markOfTheWebDeclaration(KURL(ParsedURLString, "http://foo.com--")));
     EXPECT_EQ("saved from url=(0024)http://f-%2D.com-%2D%3E/", FrameSerializer::markOfTheWebDeclaration(KURL(ParsedURLString, "http://f--.com-->")));
     EXPECT_EQ("saved from url=(0020)http://foo.com/?-%2D", FrameSerializer::markOfTheWebDeclaration(KURL(ParsedURLString, "http://foo.com?--")));
     EXPECT_EQ("saved from url=(0020)http://foo.com/#-%2D", FrameSerializer::markOfTheWebDeclaration(KURL(ParsedURLString, "http://foo.com#--")));
     EXPECT_EQ("saved from url=(0026)http://foo.com/#bar-%2Dbaz", FrameSerializer::markOfTheWebDeclaration(KURL(ParsedURLString, "http://foo.com#bar--baz")));
 }
 
 } // namespace blink