Make text-transform upper/lowercase support Turkic lang.

This is a port of Webkit change
(http://trac.webkit.org/changeset/156948) to get text-transform
upper/lowercase support Turkic (Turkish, Azerbaijane) language.

In WTF::String,
  - Add an overloading version of lower() and upper() taking a locale param.
  - Get rid of makeLower and makeUpper.
  

In RenerText, use new methods and pass a locale (the value of
lang in a given DOM node).

Elsewhere, replace make{Lower,Upper} with {lower,upper}.

This CL differs from the webkit patch: 
1) move ctor is disabled.
2) ASCIILiteral is not used (we removed it). 
3) lower(locale), upper(locale) returns PassRefPtr instead of RefPtr. 
4) StringImpl has a new mthod upconvertedString() to refactor "if 8bit, upconvert and get chart16 buffer else just get char16 buffer".
5) the way ICU API is called is slightly streamlined in lower()/upper(). 
  
BUG=304911
TEST=Layout test: fast/text/text-transform-turk*.

Review URL: https://codereview.chromium.org/26732003

git-svn-id: svn://svn.chromium.org/blink/trunk@159437 bbb929c8-8fbe-4397-9dbb-9b2b20218538