B2G/gecko/browser/devtools/shared/Undo.jsm
/**
   * Undo the top of the undo stack.
   *
   * @return true if an action was undone.
   */
Undo the top of the undo stack.
@return true if an action was undone.
Undo the top of the undo stack . @return true if an action was undone .
function Undo_canUndo()
  {
    if (!this.canUndo()) {
      return false;
    }
    this._stack[--this._index].undo();
    this._change();
    return true;
  }
function Undo_canUndo ( ) { if ( ! this . canUndo ( ) ) { return false ; } this . _stack [ -- this . _index ] . undo ( ) ; this . _change ( ) ; return true ; }
Undo the top of the undo stack.
Undo the top of the undo stack .