hints: use `window.location.href` to change current URL

hints: use `window.location.href` to change current URL

When opening a hint in the current window, we do so by emulating a
`click()` on the element that we want to switch to. This enables us to
open hints when there is no href set, e.g. when the element executes
JavaScript to change the page. Unfortunately, this method of opening
links does not work when JavaScript is disabled in the client.

If the element has a `href` attribute, we can work around this problem
by directly setting `window.location.href` to the element's reference.
Next to being a more obvious method of setting the current URL, this
also fixes hints with JavaScript disabled. Note that we still have to
keep around the old method of using `click()` on the element in case it
has no href attribute.