Restrict font-family in @font-face to <family-name>

Restrict font-family in @font-face to <family-name> by calling
consumeFamilyName directly. To make sure no generic-name is being
parsed add the test fontfaceset-invalid-family-names.html.

Behavior matches FF.

BUG=499780

Review URL: https://codereview.chromium.org/1363233002

Cr-Commit-Position: refs/heads/master@{#350479}
6 files changed