[Ozone] Disable TextUtils.GetStringWidth on Ozone

On Ozone font rendering is disabled. The test cannot get the string width
without a valid font.

NOTRY=true
BUG=320050

Review URL: https://codereview.chromium.org/167393003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251531 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251531