This commit also removes the old restyle_hints module and splits it into
multiple modules under components/style/invalidation/element/.
The basic approach is to walk down the tree using compound selectors as needed,
in order to do as little selector-matching as possible.
Bug: 1368240
MozReview-Commit-ID: 2YO8fKFygZI
This patch also makes RulesIterator not iterate over rules for which we don't
process nested rules.
There's nothing depending on this behavior right now afaik, and this will make
us duplicate less code in following patches.
Bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1357461
MozReview-Commit-ID: CaMFQtAVnJF
This makes the code cleaner, and also documents the fact that effective_rules
recurses into imports.
No we're not adding the imported stylesheets twice, and we share code with the
invalidation analysis.
MozReview-Commit-ID: DOF2AViTlmR
Apparently my whole conception of how the list of sheets in the styleset looked
like was flawled, and we only ever get one append_sheet for the topmost
stylesheet, instead of one for each.
MozReview-Commit-ID: FMClygMJkTc
