Restrict behavior of callable classes - VM implementation

[stereotype441]

This is the VM component of meta-bug #32152. See the meta-bug for details.

[mraleph]

Regis, if you have some free slot please take a look at this.

[a-siva]

@crelier It appears that there is still a missing piece with regards to callable classes
(see the CL from Jenny https://dart-review.googlesource.com/c/sdk/+/45141). Apparently
'implements Function' should be ignored in Dart 2 and something like
clas B { }
class D implements Function {
B call(B b) => b;
}
D d = new D();
print(d is Function);
Should print false, in the VM we print true now.

[crelier]

Ah, OK. I was not aware of this restriction.
Sure, I'll take care of it. Thanks!