Update JS whitespace definition for changes in Unicode 6.3

https://bugs.webkit.org/show_bug.cgi?id=127450
<rdar://15863457>

Reviewed by Oliver Hunt.

Covered by existing tests when running against a Unicode back-end that supports
Unicode 6.3 or higher.

* runtime/JSGlobalObjectFunctions.cpp: (JSC::isStrWhiteSpace): Explicitly allow
U+180E MONGOLIAN VOWEL SEPARATOR, because we need to keep recognizing all characters
that used to be whitespace.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@162575 268f45cc-cd09-0410-ab3c-d52691b4dbfc