Should not issue error on property assignments to function/class declarations in block scopes.

[DanielRosenwasser]

Reported by @OliverJAsh in #16239:

{
class Foo {}
Foo.bar = 1; // error

const Foo2 = () => {};
Foo2.bar = 1; // error

function FooBar() {}
FooBar.bar = 1; // error
}

None of these should error in JS checking. This may have to do with how we resolve function declarations in block bodies (i.e. we look them up in the containing function scope, not the block scope.

[OliverJAsh]

Thanks @DanielRosenwasser. Note the Foo2 example (function expression) also errors in the root scope.