script: Don't avoid all the mutation notification methods when the style attribute changes.

Styling was correct because of the explicit dirtiness, but still not fun.

Some things, like dynamic updates to with things like [style~="color"] ~ foo
selectors, were pretty broken, because we didn't take snapshots of those
attributes.

components/script/dom/htmllinkelement.rs

@@ -166,7 +166,7 @@ impl VirtualMethods for HTMLLinkElement {
 
     fn attribute_mutated(&self, attr: &Attr, mutation: AttributeMutation) {
         self.super_type().unwrap().attribute_mutated(attr, mutation);
-        if !self.upcast::<Node>().is_in_doc() || mutation == AttributeMutation::Removed {
+        if !self.upcast::<Node>().is_in_doc() || mutation.is_removal() {
             return;
         }