Unable to extend the DocumentFragment class

[Andrea Giammarchi]

The following code will fail the assertion that would, otherwise, pass in every other browser that implements classes.

(function () {'use strict';
  class WaitWhat extends DocumentFragment {}
  console.assert(
    (new WaitWhat) instanceof WaitWhat,
    `any instance of a DocumentFragment extend fails`
  );
}());

This is true even through Reflect.construct

(function () {'use strict';
  class WaitWhat extends DocumentFragment {}
  console.assert(
    Reflect.construct(DocumentFragment, [], WaitWhat) instanceof WaitWhat,
    `any instance of a DocumentFragment extend fails`
  );
}());

The expected behavior is that it is possible to extend the DocumentFragment as any other built-in class.

[Alexey Shvayka]

As of r256716, extending DocumentFragment (as well as other DOM constructors) works as expected.