<rdar://problem/4949018> JavaScriptCore API claims to work with UTF8 strings, but only works
        with ASCII strings
        
        * kjs/ustring.h:
        * kjs/ustring.cpp:
        (KJS::UString::Rep::createFromUTF8):
        Added. Implementation adapted from JSStringCreateWithUTF8CString().

        * API/JSStringRef.cpp:
        (JSStringCreateWithUTF8CString):
        * API/JSClassRef.cpp:
        (OpaqueJSClass::OpaqueJSClass):
        Use UString::Rep::createFromUTF8().



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@33374 268f45cc-cd09-0410-ab3c-d52691b4dbfc