Make small-caps work correctly with tr locale

Source/wtf/text/StringImpl.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google 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.
  *
@@ skipping 738 matching lines @@
     return c <= 0x7F ? WTF::isASCIISpace(c) : WTF::Unicode::direction(c) == WTF::Unicode::WhiteSpaceNeutral;
 }
 
 inline PassRefPtr<StringImpl> StringImpl::isolatedCopy() const
 {
     if (is8Bit())
         return create(characters8(), m_length);
     return create(characters16(), m_length);
 }
 
+WTF_EXPORT UChar32 toUpper(UChar32, const AtomicString& localeIdentifier);

[tkent, 2015/05/28 00:38:26]

This function needs a documentation.

StringImpl.{h,cpp} shouldn't have this function, which is unrelated to
StringImpl.

I'm not sure where is the best place.  A candidate is wtf/unicode/.  But adding
AtomicString dependency to wtf/unicode/ is also weird.

[rwlbuis, 2015/05/28 23:03:08]

Unfortunately I didn't find a place. It is especially hard because:
1. it should be inline
2. needs AtomicString

[tkent, 2015/05/29 05:49:50]

Let's put it here, and add TODO(rub.buis) about finding the best location, and
add a document of this functions.

+
 struct StringHash;
 
 // StringHash is the default hash for StringImpl* and RefPtr<StringImpl>
 template<typename T> struct DefaultHash;
 template<> struct DefaultHash<StringImpl*> {
     typedef StringHash Hash;
 };
 template<> struct DefaultHash<RefPtr<StringImpl>> {
     typedef StringHash Hash;
 };
 
 }
 
 using WTF::StringImpl;
 using WTF::equal;
 using WTF::equalNonNull;
 using WTF::TextCaseSensitivity;
 using WTF::TextCaseSensitive;
 using WTF::TextCaseInsensitive;
 
 #endif