[inferencing] Inferencing inside of closure should replace the type of 'this'

A common idiom in Groovy is to change the owner of a closure to the object that is invoking it. For example:

new Foo().run {
  someMethod()
}

Typically, the closure that is passed to run() will have its owner changed to an object of type Foo. That means someMethod() is really this.someMethod(), which is invoked on a Foo object.

I think this is a strong enough convention that we can encode this in the inferencing engine.