In https://codereview.chromium.org/38793007 and
https://codereview.chromium.org/40423003 I added new flags for enabling
the viewport meta tag. Currently, these flags aren't hooked-up to the
actual setting values yet since that would have broken numerous tests.
This CL adds the necessary flag settings to unit tests so the flags can
be enabled.

BUG=232102

Review URL: https://codereview.chromium.org/99493003

git-svn-id: svn://svn.chromium.org/blink/trunk@163065 bbb929c8-8fbe-4397-9dbb-9b2b20218538