Fix from Carston Guenther for bugzilla bug 3236.

	Fix from Carston Guenther for bugzilla bug 3236.

	attr(x) should work even if x is not present on the element.

	This is Radar bug #3584466

        Reviewed by hyatt

        Test cases added: fast/css-generated-content/013.html

        * khtml/css/cssstyleselector.cpp:
        (khtml::CSSStyleSelector::applyProperty):
        * layout-tests/fast/css-generated-content/013-expected.txt: Added.
        * layout-tests/fast/css-generated-content/013.html: Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@9351 268f45cc-cd09-0410-ab3c-d52691b4dbfc