Move String::truncate to StringImpl.

third_party/WebKit/Source/wtf/text/WTFString.h

 /*
  * (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 228 matching lines @@
     }
 
     void fill(UChar c)
     {
         if (m_impl)
             m_impl = m_impl->fill(c);
     }
 
     void ensure16Bit();
 
-    void truncate(unsigned len);
+    void truncate(unsigned length);
     void remove(unsigned start, unsigned length = 1);
 
     String substring(unsigned pos, unsigned len = UINT_MAX) const;
     String left(unsigned len) const { return substring(0, len); }
     String right(unsigned len) const { return substring(length() - len, len); }
 
     // Returns a lowercase/uppercase version of the string
     String lower() const;
     String upper() const;
 
@@ skipping 295 matching lines @@
 using WTF::emptyString;
 using WTF::emptyString16Bit;
 using WTF::charactersAreAllASCII;
 using WTF::equal;
 using WTF::find;
 using WTF::isAllSpecialCharacters;
 using WTF::isSpaceOrNewline;
 
 #include "wtf/text/AtomicString.h"
 #endif // WTFString_h