Function pointerdown

src/material/slider/slider.spec.ts:656–659

()

    }

    function pointerdown() {
      dispatchPointerEvent(input._hostElement, 'pointerdown', thumbX, thumbY);
      input.focus();
    }

    function pointerup() {
      dispatchPointerEvent(input._hostElement, 'pointerup', thumbX, thumbY);