[v8] disable ascii check once latin-1 is enabled in v8
https://bugs.webkit.org/show_bug.cgi?id=108805

Patch by Dan Carney <dcarney@google.com> on 2013-02-04
Reviewed by Kentaro Hara.

No new tests. No change in functionality.

* bindings/v8/V8ValueCache.cpp:
(WebCore::makeExternalString):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@141752 268f45cc-cd09-0410-ab3c-d52691b4dbfc