Functions with a declared this type should return that type when called with 'new'

[sandersn]

Given

interface FooType {
  x: number;
}
function Foo(this: FooType, x: number) {
  this.x = x;
}
let foo/**/ = new Foo(12);

Expected:
foo should be of type FooType

Actual:
foo is of type any.

Note: If you name the interface and the function the same thing, then the type of foo is structurally correct.

[mhegazy]

As per the discussion in the design meeting today, we should log a new issue for supporting new syntax for defining a function that can be called as a constructor.