B2G/gecko/browser/components/tabview/groupitems.js
// Gets the <Item> that should be displayed on top when in stack mode.
Gets the  that should be displayed on top when in stack mode.
Gets the that should be displayed on top when in stack mode .
function GroupItem_getTopChild() {
    if (!this.getChildren().length) {
      return null;
    }
    return this.getActiveTab() || this.getChild(0);
  }
function GroupItem_getTopChild ( ) { if ( ! this . getChildren ( ) . length ) { return null ; } return this . getActiveTab ( ) || this . getChild ( 0 ) ; }
Gets the <Item> that should be displayed on top when in stack mode.
Gets the <Item > that should be displayed on top when in stack mode .