Oilpan: move core/fileapi to oilpan's heap.

This moves the File API and its objects to Oilpan using transition
types.

R=haraken@chromium.org,tkent@chromium.org
BUG=340522

Review URL: https://codereview.chromium.org/176853004

git-svn-id: svn://svn.chromium.org/blink/trunk@168460 bbb929c8-8fbe-4397-9dbb-9b2b20218538