[cros i18n] Provide more space for step header. Fixes enrollment title for ru/sr locales.

RU title translation will be also shortened to fit updated width.

BUG=313745
NOTRY=true

Review URL: https://codereview.chromium.org/51963006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232351 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232351