Inconsistent browser behavior when using $.ajax with dataType "script" and invalid "url"

[ipernet]

Simple repro:

​http://ksimon-test.beta.svn.krds.com/jq.html

Actual result:

• The error callback is not executed by Firefox or Chrome when using dataType: "script" with $.ajax and with a 404 URL (or any other HTTP error)

• IE8+ executes the success callback, despite the url returns a 404 error.

Expected result:

Error callback should get executed if the URL cannot be loaded when using dataType: "script" for all browsers.

Or at least IE should not execute the success callback in such case.

[dmethvin]

Duplicate of #12362.