Avoid applying invalid media attribute
Created attachment 249825 [details]
When <link rel=stylesheet> with an invalid media attribute was part of the HTML, I saw that it resulted in a non-empty MediaQuerySet, containing a single query with no expressions. (which didn't have its m_ignored flag on)
Therefore I added an extra check that makes sure that the queries handled by MediaQueryEvaluator::eval have expressions, and if not, they are treated as ignored.
I accidentally filed that as a separate issue, when I should have added a patch on the original bug.
*** This bug has been marked as a duplicate of bug 143262 ***