The following tests fail in a --disable-webrtc build. They should not be run:

dom/bindings/test/test_jsimplemented_subclassing.html
dom/bindings/test/test_exceptions_from_jsimplemented.html
dom/tests/mochitest/general/test_interfaces.html
dom/tests/mochitest/general/test_interfaces_secureContext.html

The best thing to do here would be to detect when we are building with
--disable-webrtc and not run these tests. However that does not seem to be
possible so instead we'll disable them on the only build that has webrtc
disabled (the mingwclang build).

There's a r+ patch which didn't land and no activity in this bug for 2 weeks.
:tjr, could you have a look please?
For more information, please visit auto_nag documentation.

Depends on D38034

I abandoned https://phabricator.services.mozilla.com/D38035 but it is still relevant if we ever revisit it.
Also https://phabricator.services.mozilla.com/D38034