Files.app: Add a semicolon to util.js.

This CL fixes the code style.

BUG=none
TEST=none
TBR=mtomasz@chromium.org

Review URL: https://codereview.chromium.org/84923003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237015 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237015