Elements with style attribute containing `display: none !important` won't hide

[gorhill]

As seen on this page: http://testabc.duapp.com/TestAd/ (Because this remote server is slow, I made a copy of the test case here: http://raymondhill.net/httpsb/ublock.html)

Using filter testabc.duapp.com###ad does not cause the target element to become hidden. (Use raymondhill.net###ad for the copy of the test case).

Issue raised here: http://www.firefox.net.cn/read-49582-2