Bug 1048780 - Call the standard matches() rather than the proprietary mozMatchesSelector(); r=jst

This also includes a test that mozMatchesSelector is still exposed and works.

--HG--
rename : js/xpconnect/tests/chrome/test_mozMatchesSelector.xul => js/xpconnect/tests/chrome/test_matches.xul
rename : js/xpconnect/tests/mochitest/file_mozMatchesSelector.html => js/xpconnect/tests/mochitest/file_matches.html