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

IE11 fixed the checkbox defaultValue issue but not textarea. Rather than
creating a new detect name I'm reusing the old one to protect anyone who
is unwisely using this externally. Re-fixing the defaultValue when it
doesn't need to be done is not a problem, so leave that code for IE11.

Fixes #14716
Closes gh-1495

Chrome 31 reports incorrect offsetWidth on a table cell with fixed width.
This is fixed in Chrome 32 so let’s just skip the failing test in Chrome 31.
See https://code.google.com/p/chromium/issues/detail?id=290399

Ref b8d0d54a
Fixes #14701

This hook was relevant for BlackBerry 4.7 which is no longer supported.

But this code path now raises error in IE10-11 (#14686) in 1.x-master branch.
So to just to be safe, also add test for IE issue to this branch too.

This check is redundant since jQuery.fragments object does not exist anymore

Fixes #14657

Closes gh-1479

Closes gh-1476

Fixes #14623
Closes gh-1473

Instead of duplicating the supported browsers matrix, just link to
the browser support page on jquery.com.

Closes gh-1430

Fix #14040
Close gh-1457

For CommonJS environments where the global already has a document, it is expected
that if a global is needed, the user can attach the global.

Fixes #14645.

- It is intentionally invalid semver as pre versions should never be released
- UI and Mobile already do this

Fix #14584

Fixes #14016.

Ref #14016

And remove unused "which" package

Closes gh-1458