Remove unneeded updateFont call in styleForKeyframe

We only need to call updateFont after applying properties that use the
FontBuilder, but these are currently all in the high priority pass.

Review URL: https://codereview.chromium.org/434503002

git-svn-id: svn://svn.chromium.org/blink/trunk@179280 bbb929c8-8fbe-4397-9dbb-9b2b20218538