ash: In vertical clock, right-align single-digit hours

Based on UX feedback we want to display times like 1:45 PM as:

 1
45

regardless of shelf aligned left or right.

BUG=297042
TEST=visual
R=harrym@chromium.org

Review URL: https://codereview.chromium.org/24281010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225190 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225190