a link) and `button` (find a button) methods.
no path (e.g. `http://localhost`).
option `userAgent`. There was an error with `browser.location`: documentation said it returns a `Location` object but also just a URL. Since `Location` object is more consistent with `window.location`, accepted that interpretation. `Location.assign` did not load a page if the page was already loaded in the browser. Changed it to load the page (add caching later on).
true/false (was a function), and separately a method called `log` that logs messages when debugging is enabled.
existing `Browser` object or for the duration of a request by passing them as second argument to `visit`.
browser to execute scripts.
handle innerHTML (full document parsing still handled by HTML5).