Reevaluate compositing requirements after next layout when fixed position elements are marked as out of viewport

BUG=279479

Review URL: https://chromiumcodereview.appspot.com/23448009

git-svn-id: svn://svn.chromium.org/blink/trunk@157154 bbb929c8-8fbe-4397-9dbb-9b2b20218538