Cosmetic filtering: cases to solve for next release

[gorhill]

Verify that the new cosmetic filtering operators solve these cases for next release -- will add them as I stumble onto them):

• http://forum.pcastuces.com/envahi_par_des_popup-f25s77301.htm (source): the empty ad placeholders should be removed.
• http://www.merriam-webster.com/dictionary/underwater (source): the dynamically added ads should be removed. Fixed with uBlockOrigin/uAssets@fb3621b.
• https://github.com/reek/anti-adblock-killer/issues/1618 (source): the anti-blocker should be neutralized.
• http://go.mail.ru/search?fr=main&q=%D1%88%D0%B0%D0%BF%D0%BA%D0%B0 (source): the dynamically generated ads in the results should be removed.

This verification list is to ensure the new cosmetic filtering operators work as expected.