Oilpan: Use transition types for HTMLDocument.

BUG=357163
R=haraken@chromium.org

Review URL: https://codereview.chromium.org/296513007

git-svn-id: svn://svn.chromium.org/blink/trunk@174512 bbb929c8-8fbe-4397-9dbb-9b2b20218538