code: function bodyContains($obj) {
  	var id = $obj.attr('id'),
  		el = id ? env.window.document.getElementById(id) : null;
  	// must also check that the element with the id is the one we want
  	return el ? el === $obj[0] : $.contains(env.window.document.body, $obj[0]);
  }
docs: A fast function to check if an element is still in the DOM. It
  tries to use an id as ids are indexed by the browser, or falls
  back to jQuery's `contains` method. May fail if two elements
  have the same id, but so be it
  
  @param {object} $obj A jQuery-wrapped HTML element
  @return {boolean}