We can't feature detect ActiveX in IE11, but we can just call
it and catch whatever error occurs, then try normal XHR.

This also reduces memory leaks if the element is removed without cleaning
events (e.g with native DOM operations).

Not pickable into the 1.x branch because oldIE still needs this.

(cherry picked from commit 60a61781)

Conflicts:

	src/ajax/parseJSON.js

In 1.x if the support test executes before doc ready, it may not be able
to return a result yet. In such a case, we protect ourselves from future
breakages, allowing only for the ones before doc ready.

Since in 2.x lazy support tests attach test elements to docElem, not body,
such a guard is unnecessary.

The issue was fixed in grunt-contrib-uglify:
https://github.com/gruntjs/grunt-contrib-uglify/issues/22

Close gh-1423

Had some weird failures in IE with xhr build of 1.9.1

Close gh-1407

Close gh-1405

Close gh-1396

(cherry picked from commit 126d596b)

Conflicts:

	src/data.js
	src/data/accepts.js
	test/unit/core.js
	test/unit/data.js

(cherry picked from commit 346b031af9e3b315ef351a9cc7fee56f930cf346)

Conflicts:

	src/traversing.js