TypeScript: Extending HTMLElement still not working

TypeScript Version: 2.1.4

Code

So the following JS works fine in Chrome (v55)

class MyCustomElement extends HTMLElement {
    constructor() {
        super();
        this.foo = "bar";
    }

    doSomething() {
        console.log(this.foo);
    }
}

customElements.define("my-custom-element", MyCustomElement);

Which of course can be represented with the following TypeScript:

class MyCustomElement extends HTMLElement {
    foo: string;
    constructor() {
        super();
        this.foo = "bar";
    }

    doSomething() {
        console.log(this.foo);
    }
}

customElements.define("my-custom-element", MyCustomElement);

Except the compiled typescript won’t run

tsc Output

var __extends = (this && this.__extends) || function (d, b) {
    for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
    function __() { this.constructor = d; }
    d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
var MyCustomElement = (function (_super) {
    __extends(MyCustomElement, _super);
    function MyCustomElement() {
        var _this = _super.call(this) || this;
        _this.foo = "bar";
        return _this;
    }
    MyCustomElement.prototype.doSomething = function () {
        console.log(this.foo);
    };
    return MyCustomElement;
}(HTMLElement));
customElements.define("my-custom-element", MyCustomElement);

In Chrome’s console i see:

Uncaught TypeError: Failed to construct ‘HTMLElement’: Please use the ‘new’ operator, this DOM object constructor cannot be called as a function.