Add "enter" handling on image selection part of supervised user creation screen.

BUG=294478
R=ygorshenin@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/26238004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228966 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228966
Roll ANGLE.

TEST=tree
BUG=
TBR=kbr@chromium.org

Review URL: https://codereview.chromium.org/26155006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228967 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228967