Move String::truncate to StringImpl.

third_party/WebKit/Source/wtf/text/StringImpl.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller ( mueller@kde.org )
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Andrew Wellington (proton@wiretapped.net)
  *
  * 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
@@ skipping 879 matching lines @@
     int32_t realLength = Unicode::foldCase(data, length, characters16(), m_length, &error);
     if (!error && realLength == length)
         return newImpl.release();
     newImpl = createUninitialized(realLength, data);
     Unicode::foldCase(data, realLength, characters16(), m_length, &error);
     if (error)
         return this;
     return newImpl.release();
 }
 
+PassRefPtr<StringImpl> StringImpl::truncate(unsigned length)
+{
+    if (length >= m_length)
+        return this;
+    if (is8Bit())
+        return create(characters8(), length);
+    return create(characters16(), length);
+}
+
 template <class UCharPredicate>
 inline PassRefPtr<StringImpl> StringImpl::stripMatchedCharacters(UCharPredicate predicate)
 {
     if (!m_length)
         return empty();
 
     unsigned start = 0;
     unsigned end = m_length - 1;
 
     // skip white space from start
@@ skipping 1141 matching lines @@
         } else if (localeIdMatchesLang(localeIdentifier, "lt")) {
             // TODO(rob.buis) implement upper-casing rules for lt
             // like in StringImpl::upper(locale).
         }
     }
 
     return toUpper(c);
 }
 
 } // namespace WTF