DevTools: fix front-end compilation erros introduced in r184041

BUG=410701
R=loislo@chromium.org

Review URL: https://codereview.chromium.org/667083002

git-svn-id: svn://svn.chromium.org/blink/trunk@184050 bbb929c8-8fbe-4397-9dbb-9b2b20218538