Generic parameters with default values loose external context

```ts
class Foo<T> {
  foo<U extends ArrayLike<T> = Array<T>>(): void {}
}

let a = new Foo<i32>();
a.foo();
```
output:
```bash
;; ERROR TS2304: Cannot find name 'T'.
;;    :
;;  2 │ foo<U extends ArrayLike<T> = Array<T>>(): void {}
;;    │                                    ~
;;    └─ in module.ts(2,38)
```
Related to #2446 
