JSON linter: don't allow version_added === version_removed

[a2sheppy]

We have a couple of places here and there where version_added is invalidly the same as version_removed; we need to update the linter to catch this.

[ddbeck]

Would you mind sharing a couple of these examples?

[a2sheppy]

I just submitted a PR that will fix them, but RTCPeerConnection.onaddstream has this problem, for instance:

https://github.com/mdn/browser-compat-data/blob/master/api/RTCPeerConnection.json#L1999

[ExE-Boss]

I’m also fixing https://github.com/mdn/browser-compat-data/blob/master/api/RTCPeerConnection.json#L1999 in #1712.

[queengooborg]

+1 for this. Having a feature removed in the same version it was introduced in doesn’t make any sense!

[Elchi3]

I thought this would be checked here https://github.com/mdn/browser-compat-data/blob/master/test/test-versions.js#L51

But maybe it is suitable to test this in the consistency tests as well. I haven't reviewed it yet.

[ExE-Boss]

The test should be compareVersions(a, b) >= 0.