StackOverflow typecheking code with some SRTPs

[majocha]

Unfortunately, I don't have a very small repro.

Send this gist to fsi. It will stack overflow with endless loop in FSharp.Compiler.TypedTreeOps.accFreeInTypes

Comment out line 274:

member inline this.Bind(awaitable: Awaitable<_, _, _>, continuation) = this.Bind(awaitable.GetAwaiter(), continuation)

and it will be fine again.