The new css tree may change the order of selectors (keeping the
same semantics). This affects how the selectors are printed later,
which causes some css parsing tests to not match the references.
Fortunately the order is consistent between runs given the same
css, so we just have to switch around the order in some of the
.ref.css files.
Previously we kept a Selector object for every "simple selector" (term
from CSS spec). Now we keep one for every match operation. So given the
selector
".a b:focus"
we will have 4 elements:
- pseudoclass ":focus"
- element "b"
- match any desendant (the space)
- class ".a"
Each of those is represented by a "selector class" which is basically
the collection of vfuncs for this selector.
