menu looses external class

[pvamshi]

As we have code like this :

if we add menu with a class

<mdc-menu class="abc">

Expected

<mdc-menu class="abc mdc-simple-menu topLeft mdc-simple-menu--open">

Actual

<mdc-menu class="mdc-simple-menu topLeft mdc-simple-menu--open">

[pvamshi]

Another trivial issue :

open(focusIndex: number) {
    if (!this.isOpen()) {
      this._foundation.open({ focusIndex: focusIndex });
    }
}

focusIndex should be optional

open(focusIndex?: number) {
    if (!this.isOpen()) {
      this._foundation.open({ focusIndex: focusIndex });
    }
}

Right now its giving typescript error and forcing to pass a number