Document().make() creates a new tab instead of a new window

Followup to https://orionfeedback.org/d/4439-opening-new-window-window-with-applescript-jxa-does-not-work-like-in-safari.

That issue was marked as done, but the behaviour is incorrect when compared to Safari. In Safari, making a new document creates a new window but in Orion in creates a new tab, making it similar to https://orionfeedback.org/d/4438-switching-to-new-tab-via-applescript-jxa-segfaults (which is behaving correctly).

Furthermore, this behaves weirdly in the sense that if there is more than one window, the code always creates the new tab in the one which is not frontmost. But either way the code should be creating a new window on the front so as to be consistent with Safari.

Tested on Orion 0.99.124.1-beta (WebKit 616.1.10).