XSSAuditor should use threadSafeMatch when relevant.
https://bugs.webkit.org/show_bug.cgi?id=111099

Reviewed by Adam Barth.

Given the work on breaking parsing out into a background thread, we
should compare QualifiedNames in a thread-safe manner. Rather than
casting the result of QualifiedName::localName to a String, we can
call out to threadSafeMatch to do the comparison.

This patch leaves one use of equalIgnoringNullity in
XSSAuditor::findAttributeWithName. That usage seems safe, since we're
creating a new string against which to compare.

* html/parser/XSSAuditor.cpp:
(WebCore::hasName):
    Replace call to equalIgnoringNullity(Vector<UChar...>, String)
    with threadSafeMatch(String, QualifiedName).


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@144425 268f45cc-cd09-0410-ab3c-d52691b4dbfc