Remove zoom argument from family-setting FontBuilder functions.

A follow-up to https://codereview.chromium.org/200573006/,
does the same thing to font-family.

R=eae
BUG=

Review URL: https://codereview.chromium.org/200953003

git-svn-id: svn://svn.chromium.org/blink/trunk@169286 bbb929c8-8fbe-4397-9dbb-9b2b20218538