[webrtc-pc] Test coverage chapter 6 (#2463)

alvestrand has just created a new issue for https://github.com/w3c/webrtc-pc:

== Test coverage chapter 6 ==
This is a sub-issue for #2442, keeping notes. This reviews only whether items are properly marked as testable (red or green) or not testable (white).

- 6.1
-- createDataChannel step 16 should be testable.
-- createDataChannel step 22 is not testable (no JS-visible effect)
-- 6.1.1.3 connected procedure - step 4 should be testable (and tested)
- 6.2
-- 6.2.5 and 6.2.6 probably make more sense to attach the test to the overall procedure, not the steps.
-- 6.4 garbage collection should have all its bullets testable (not sure - is garbage collection testable? but if not, the header line shouldn't be red either)




Please view or discuss this issue at https://github.com/w3c/webrtc-pc/issues/2463 using your GitHub account