Tests: ensure support tests are failed by at least one tested browser
Tests: ensure support tests are failed by at least one tested browser

A whitelist is available so that some tests can be allowed to always succeed.
This is used only for ajax for now as it can be manually disabled in IE but
is enabled by default.

Closes gh-4052

jquery/jquery,roytoo/jquery,jquery/jquery,roytoo/jquery,roytoo/jquery,jquery/jquery