[Sheriff-o-matic] Add persistence to ct-tree-select through core-localstorage

BUG=400401
NOTRY=true

Review URL: https://codereview.chromium.org/480233003

git-svn-id: svn://svn.chromium.org/blink/trunk@180585 bbb929c8-8fbe-4397-9dbb-9b2b20218538