[analyzer] Implement function tearoff equality corner cases

[eernstg]

This is the analyzer specific version of #46834, which has the details. It seems likely that there is no work to do here, because the analyzer configurations are passing the tests.

[jcollins-g]

P3 only based on this being a theoretical problem and our tests passing; we should still confirm this is OK.

[devoncarew]

@eernstg - is this part of the constructor tearoff work?

cc @srawlins

[eernstg]

@devoncarew

is this part of the constructor tearoff work?

Leaf and I discussed this. There should not be a need to guard this feature by an experiment flag, but it would be good if it can fit into the schedule with the October milestone.

[devoncarew]

@srawlins - pinging this issue. This is currently part of the work we expect to ship for the next stable - branching in ~8 days. Do you expect to have this done by then (or should we re-plan)?

[scheglov]

The analyzer is not affected by this change, we don't evaluate anything if it is not a constant.

We could do a small tweak to support runtime type equality.
https://dart-review.googlesource.com/c/sdk/+/217284