Oilpan: Prepare moving meter/progress/summary ua shadow dom elements to oilpan.

BUG=357163

Review URL: https://codereview.chromium.org/278823003

git-svn-id: svn://svn.chromium.org/blink/trunk@173886 bbb929c8-8fbe-4397-9dbb-9b2b20218538