Bug description

Similar to #108, the VSTHRD003 analyzer failed to recognize a deadlock-prone pattern of a JTF.Run delegate that simply returns the value of a Task field.

Repro steps

See this PR (line 314) for the specific case the analyzer failed to catch the issue.

Roughly this:

Task task;

void Foo()
{
   task = jtf.RunAsync(async () => { await Task.Yield(); }).Task;
   jtf.Run(() => task); // violation should be found here.
}

Expected behavior

We should see a VSTHRD003 diagnostic as indicated above.

Actual behavior

No VSTHRD003 diagnostic.