[DDC] Implement support for dynamic checks on parameters that are covariant-by-declaration due to inheritance

[eernstg]

This is the DDC specific issue for #47072, which has the details.

[devoncarew]

@nshahan (or @sigmundch) - can you provide a very rough estimate of how long this would take to do? We're trying to get breadbox estimates of the ~5 impl. tasks for this language change.

[nshahan]

@eernstg If the tests you added in https://dart-review.googlesource.com/c/sdk/+/208504 are all passing in DDC already is it reasonable to close this issue?

[eernstg]

Wouldn't DDC receive kernel code from the CFE? In that case it is probably a good idea to wait for completion of #47074, and then re-check that it still works.

[devoncarew]

@nshahan - assigning you as the likely owner.

[johnniwinther]

This is already handled in DDC.