Add back i18n-values=.*font{Family,fontSize} for now
Interstitial pages are loaded via data url and cannot access
chrome://text_default.css. Until the way they're loaded is changed,
we have to use the old way.
While I'm at it, I made supervised_user_block_interstitial.html use
IDS_WEB_FONT_FAMILY instead of the hard-coded fonts in the corresponding
css. This change is for bug 303849.
BUG=443203,303849
TEST=See comment 4 in the bug 443203. See also http://crbug.com/444698
Review URL: https://codereview.chromium.org/
808753006
Cr-Commit-Position: refs/heads/master@{#310142}