CSS Animations: add interpolation test for outline-offset

Crashes in the virtual/web-animations-css/animations suite, add an
exception for that.

BUG=258896

Review URL: https://chromiumcodereview.appspot.com/23757019

git-svn-id: svn://svn.chromium.org/blink/trunk@157194 bbb929c8-8fbe-4397-9dbb-9b2b20218538