Auto merge of #16456 - bholley:bloom_children, r=emilio

Use the bloom filter for child selectors

This speeds up bloom-basic-ref.html by 4x on my machine.

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components/selectors/matching.rs

@@ -122,6 +122,7 @@ fn may_match<E>(mut selector: &ComplexSelector<E::Impl>,
     loop {
          match selector.next {
              None => break,
+             Some((ref cs, Combinator::Child)) |
              Some((ref cs, Combinator::Descendant)) => selector = &**cs,
              Some((ref cs, _)) => {
                  selector = &**cs;