Selector: Only attach the unload handler in IE & Edge Legacy

Selector: Only attach the unload handler in IE & Edge Legacy

Both IE & Edge Legacy need the workaround of calling `setDocument()` in an
`unload` handler to avoid "permission denied" errors. However, due to not being
possible to feature-detect this issue, the handler has been applied in all
browsers for windows different than the one in which jQuery was loaded.

jQuery 4.0, which drops Edge Legacy support, guards this workaround with
a `document.documentMode` check. This won't work in the 3.x line due to still
supporting Edge Legacy but we can check for
`document.documentElement.msMatchesSelector` instead as that API is
supported in IE 9+ and all Edge Legacy versions.

Fixes gh-5281
Closes gh-5282
Ref gh-4792