onbeforeunload doesn't work on iOS 6-7

[m_gol]

iOS doesn't seem to support the onbeforeunload event but window.onbeforeunload is null which makes our test suite believe it's supported and run the test. :(

This is the only test that's failing in iOS6, fixing/workarounding it would make it possible to register iOS6 in TestSwarm. (iOS7 fails more tests so that would come later).

I have no idea how to blacklist this test in Mobile Safari without resorting to UA sniffing.

[m_gol]

The problem is a support test would have to effectively trigger unload and if beforeunload is not supported there's no way to cancel the unload. :/

[m_gol]

PR: ​https://github.com/jquery/jquery/pull/1496

[Michał Gołębiowski]

Tests: Blacklist beforeunload test in iOS

iOS has the window.onbeforeunload field but doesn't support the beforeunload handler making it impossible to feature-detect the support.

Fixes #14717 Closes gh-1496

Changeset: 988d99ad278c2c9dc16c68f86bddc4df99dcd928

[dmethvin]

I'm thinking we may want to close this actual ticket as cantfix and we probably need somewhere to document this. That part is stumping me though, because a note in the API docs is likely to be overlooked. Perhaps Google will find this ticket.

[m_gol]

You're right, it's not fixed per se, I just blacklisted a failing test so that the build passes. Definitely cantfix.