JS: Can't assign to superclass property

TypeScript Version: 3.1.0-dev.20180807

Code

a.js

class A {
    constructor() {
        this.initializer = 2;
    }
}

class B extends A {
    constructor() {
        super();
        this.initializer = this.initializer + 1;
    }
}

Expected behavior:

No error.

Actual behavior:

src/a.js:10:9 - error TS7022: 'initializer' implicitly has type 'any' because it does not have a type annotation and is referenced directly or indirectly in its own initializer.

10         this.initializer = this.initializer + 1;

[sandersn]

Ideally, I think the solution is to check this.initializer in B as if its initaliser were super.initalizer + 1, since that is the intent (and no matter what @RyanCavanaugh tells me, is 10 times saner than this.i = this.i + 1).

However, we're not well equipped to do this, I think. checkThisExpression would have to know to delegate to checkSuperExpression, and I think the check for that would be brittle.