anchor.diff:  
     /**
      * Set the enclosing element of this element to the given [element].
  -   *
  -   * Throws [FrozenHashCodeException] if the hashCode can't be changed.
      */
     void set enclosingElement(Element element) {
       _enclosingElement = element as ElementImpl;
  
positive.code: 
    /**
     * Changes the name of this element.
     *
     * Throws [FrozenHashCodeException] if the hashCode can't be changed.
     */
    void set name(String name) {
      this._name = name;
  
negative.code:   /**
     * Sets the offset of the name of this element in the file that contains the
     * declaration of this element.
     */
    void set nameOffset(int offset) {
      _nameOffset = offset;
  