SelectorQuery should update distribution before execute a given query.

If a given selector needs crossing tree boundaries and document has
childNeedsDistributionRecalc, need to update distribution before
execute.

BUG=337618
TEST=fast/dom/shadow/querySelector-with-distribution.html

Review URL: https://codereview.chromium.org/240473008

git-svn-id: svn://svn.chromium.org/blink/trunk@172016 bbb929c8-8fbe-4397-9dbb-9b2b20218538