style: Remove hashes from style rules and dependencies.

Dependencies are very numerous, and now we shouldn't be getting so many of them.

Style rules just don't need them, so it's a waste of memory.

components/style/selector_map.rs

@@ -202,7 +202,7 @@ impl SelectorMap<Rule> {
         for rule in rules {
             if matches_selector(&rule.selector,
                                 0,
-                                &rule.hashes,
+                                Some(&rule.hashes),
                                 element,
                                 context,
                                 flags_setter) {