Enable layout test for font fallback with identical family names

BUG=285303
R=eae,eseidel,behdad

Review URL: https://codereview.chromium.org/376953002

git-svn-id: svn://svn.chromium.org/blink/trunk@177736 bbb929c8-8fbe-4397-9dbb-9b2b20218538