Reviewed by Geoffrey Garen.

        Freezing a function and its prototype causes browser to crash.
        https://bugs.webkit.org/show_bug.cgi?id=61758

        Add test to ensure correct behaviour

        * fast/js/preventExtensions-expected.txt:
        * fast/js/script-tests/preventExtensions.js:
        (f):
2011-05-31  Oliver Hunt  <oliver@apple.com>

        Reviewed by Geoffrey Garen.

        Freezing a function and its prototype causes browser to crash.
        https://bugs.webkit.org/show_bug.cgi?id=61758

        Make JSObject::preventExtensions virtual so that we can override it
        and instantiate all lazy

        * JavaScriptCore.exp:
        * runtime/JSFunction.cpp:
        (JSC::createPrototypeProperty):
        (JSC::JSFunction::preventExtensions):
        (JSC::JSFunction::getOwnPropertySlot):
        * runtime/JSFunction.h:
        * runtime/JSObject.h:
        * runtime/JSObject.cpp:
        (JSC::JSObject::seal):
        (JSC::JSObject::seal):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@87826 268f45cc-cd09-0410-ab3c-d52691b4dbfc