Add --force-compositing-mode to serviceworker and targetedstylerecalc.

These virtual suites show no failures with FCM on linux.

R=enne, ojan
BUG=361729

Review URL: https://codereview.chromium.org/274193002

git-svn-id: svn://svn.chromium.org/blink/trunk@173774 bbb929c8-8fbe-4397-9dbb-9b2b20218538