Bug 1966586 - Reuse other browser windows when opening _blank links in Taskbar Tabs windows. r=nrishel
This doesn't affect other tab additions, nor does it stop the tab bar
from appearing altogether. The idea is that _if_ another tab is somehow
made, the user should see it; but we should not create new tabs if we
can avoid it.
This also adds tests for opening URIs in popups and taskbar tabs to make
it less likely that this breaks in future.
Differential Revision: https://phabricator.services.mozilla.com/D253726
<!DOCTYPE html><metacharset="utf-8"><title>CSS Values and Units Test: support for the ch unit</title><linkrel="author"title="Cameron McCormack"href="mailto:cam@mcc.id.au"><linkrel="help"href="https://drafts.csswg.org/css-values-3/#font-relative-lengths"><linkrel="match"href="reference/ch-unit-016-ref.html"><metaname="assert"content="In vertical upright writing modes, the ch unit is equal to the vertical advance of the zero glyph."><style>@font-face{font-family:ChTestShortZero;src:url(resources/ChTestShortZero.woff);}div{height:10px;background-color:blue;margin-top:10px;}.test{writing-mode:vertical-rl;text-orientation:upright;width:5ch;}.ref{width:100px;}</style><p>The test passes if there are two blue rectangles of equal length.</p><!-- ChTestShortZero has a '0' glyph whose vertical advance is a quarter of the units per em, so ch units in vertical upright writing modes should compute to 0.25em, resulting in the div being 100px width. --><divclass="test"style="font: 80px ChTestShortZero;"></div><divclass="ref"></div>