Bug
1798485 - Add support for the `contentvisibilityautostatechange` event r=emilio
Add support for the contentvisibilityautostatechange and fire it when
the relevancy of `content-visibility: auto` elements change.
This commit also makes some changes to the
content-visibility-auto-state-changed.html test. Two more subtests are
added which verifies that an event is sent after `content-visibility:
auto` is applied to an element. Finally the `top` element is renamed to
`upper` as `top` can also refer to the top-level Window and it seems
that Gecko has a different precedence when accessing variables in
script.
Differential Revision: https://phabricator.services.mozilla.com/
D161140