Remove 'String::append' from some of the blink source.

Source/platform/network/HTTPParsers.cpp

 /*
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. http://www.torchmobile.com/
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2011 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:
@@ skipping 111 matching lines @@
             || c == '/' || c == '[' || c == ']' || c == '?' || c == '='
             || c == '{' || c == '}')
         return false;
     }
     return true;
 }
 
 static const size_t maxInputSampleSize = 128;
 static String trimInputSample(const char* p, size_t length)
 {
-    String s = String(p, std::min<size_t>(length, maxInputSampleSize));
-    if (length > maxInputSampleSize)
-        s.append(horizontalEllipsis);
-    return s;
+    if (length > maxInputSampleSize) {
+        String s = String(p, std::min<size_t>(length, maxInputSampleSize)) + horizontalEllipsis;
+        return s;
+    }
+    return String(p, std::min<size_t>(length, maxInputSampleSize));
 }
 
 ContentDispositionType contentDispositionType(const String& contentDisposition)
 {
     if (contentDisposition.isEmpty())
         return ContentDispositionNone;
 
     Vector<String> parameters;
     contentDisposition.split(';', parameters);
 
@@ skipping 533 matching lines @@
 
 size_t parseHTTPRequestBody(const char* data, size_t length, Vector<unsigned char>& body)
 {
     body.clear();
     body.append(data, length);
 
     return length;
 }
 
 }