Add pass / fail indicator to document title

QUnit now adds a tick or cross to document.title, nodeunit should do the same when running in the browser.

No files or tests are named. Start by locating nodeunit's browser runner and the code that controls the browser document title. Done means browser runs visibly mark document.title with a pass or fail indicator, matching the requested behavior.

索引モデルが issue の本文から書いたものです。