[selectors] Reconsider to not drop whole selector list containing an invalid selector

Source: http://dev.w3.org/csswg/selectors/#invalid-selector

Dropping whole selector list containing an invalid selector would lead to
many future errors.

* Why not just to ignore the invalid selector styling?
* What is the benefit of dropping whole selector list? The performance?

Today's vendor prefixes leaded problem: @-webkit-keyframes,@keyframes{} is
be shorter then to repeat whole style list again and again. And repeating
same thing leads to maintenance and performance problems.


Binyamin