Don't update distribution for ::slotted selector matching

A selector matching for "::slotted" uses a "node -> slot" lookup,
but it doesn't use a slot's assigned nodes.

Given that, we don't need to update distribution for ::slotted because the status of
slot's assigned nodes doesn't matter here.

It looks that was introduced at:
https://chromium.googlesource.com/chromium/src/+/38a8b698b864db5dadba51bbda82cc07d3cc2b93

Change-Id: I38e7e8ea0dd104a059a671a5d314b5df89000417
Reviewed-on: https://chromium-review.googlesource.com/1011528Reviewed-by: Takayoshi Kochi <kochi@chromium.org>
Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Hayato Ito <hayato@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550566}

third_party/blink/renderer/core/css/css_selector.cc

@@ -1082,7 +1082,6 @@ bool CSSSelector::NeedsUpdatedDistribution() const {
   return ForAnyInTagHistory(
       [](const CSSSelector& selector) -> bool {
         return selector.RelationIsAffectedByPseudoContent() ||
-               selector.GetPseudoType() == CSSSelector::kPseudoSlotted ||
                selector.GetPseudoType() == CSSSelector::kPseudoHostContext;
       },
       *this);