make -1s red in gerrit new screen

the following css attribute selector will make -1s in the english
ui version of gerrit new screen be the color red. This is as good
as we can do today given that gerrit doesn't provide real classes
on things any more.

Reference on attr selectors: http://css-tricks.com/attribute-selectors/
(should work on all browsers > ie6)

A follow up will be to see if we can get proper semantic tags back
into gerrit for things like this.

Change-Id: I8236cf83b648bfe352daea1f3ae59c151068ab44
Merge "make -1s red in gerrit new screen"