code: function tabView_closeTab(aSpec) { 
      var spec = aSpec || {};
      var tab = spec.tab;
  
      if (!tab) {
        throw new Error(arguments.callee.name + ": Tab not specified.");
      }
  
      var button = this.getElement({
        type: "tab_closeButton",
        value: tab}
      );
      this._controller.click(button);
    }
docs: Close a tab
  
  @param {object} aSpec
  Information about the element to operate on
  Elements: tab - Tab to close