Oilpan: Enable Oilpan by default for device_orientation/

This CL just drops WillBe types from device_orientation/.

BUG=340522

Review URL: https://codereview.chromium.org/539833002

git-svn-id: svn://svn.chromium.org/blink/trunk@181371 bbb929c8-8fbe-4397-9dbb-9b2b20218538