Inline consoleAgent variable in WorkerInspectorController constructor

BUG=None
R=alph@chromium.org

Review URL: https://codereview.chromium.org/101323011

git-svn-id: svn://svn.chromium.org/blink/trunk@163961 bbb929c8-8fbe-4397-9dbb-9b2b20218538