code: function isInputEventFromLabelClick(event) {
    return lastLabelClickPos
        && lastLabelClickPos.x == event.x
        && lastLabelClickPos.y == event.y;
  }
docs: Gets whether the given event is an input event that was caused by clicking on an
  associated label element.
  
  This is necessary because the browser will, upon clicking on a label element, fire an
  *extra* click event on its associated input (if any). mdGesture is able to flag the label
  click as with `$material` correctly, but not the second input click.
  
  In order to determine whether an input event is from a label click, we compare the (x, y) for
  the event to the (x, y) for the most recent label click (which is cleared whenever a non-label
  click occurs). Unfortunately, there are no event properties that tie the input and the label
  together (such as relatedTarget).
  
  @param {MouseEvent} event
  @returns {boolean}