anchor.diff:     */
     ClassElementImpl _enclosingClass;
   
  -  ClassElement get enclosingClass => _enclosingClass;
  -
  -  /**
  -   * For consumers of error verification as a library, (currently just the
  -   * angular plugin), expose a setter that can make the errors reported more
  -   * accurate when dangling code snippets are being resolved from a class
  -   * context. Note that this setter is very defensive for potential misuse; it
  -   * should not be modified in the middle of visiting a tree and requires an
  -   * analyzer-provided Impl instance to work.
  -   */
  -  set enclosingClass(ClassElement classElement) {
  -    assert(classElement is ClassElementImpl);
  -    assert(_enclosingClass == null);
  -    assert(_enclosingEnum == null);
  -    assert(_enclosingFunction == null);
  -    _enclosingClass = classElement;
  -  }
  -
     /**
      * The enum containing the AST nodes being visited, or `null` if we are not
      * in the scope of an enum.
  
positive.code:           return;
          }
        }
  
        return reportTypeError();
      }
      // TODO(leafp): Delete this non Dart 2 path
      DartType staticReturnType = _computeReturnTypeForMethod(returnExpression);
  
negative.code:     _DISALLOWED_TYPES_TO_EXTEND_OR_IMPLEMENT = _typeProvider.nonSubtypableTypes;
      _typeSystem = _currentLibrary.context.typeSystem;
      _options = _currentLibrary.context.analysisOptions;
    }
  
    ClassElement get enclosingClass => _enclosingClass;
  
    /**
     * For consumers of error verification as a library, (currently just the
     * angular plugin), expose a setter that can make the errors reported more
     * accurate when dangling code snippets are being resolved from a class
     * context. Note that this setter is very defensive for potential misuse; it
     * should not be modified in the middle of visiting a tree and requires an
     * analyzer-provided Impl instance to work.
     */
    set enclosingClass(ClassElement classElement) {
      assert(classElement is ClassElementImpl);
      assert(_enclosingClass == null);
      assert(_enclosingEnum == null);
      assert(_enclosingFunction == null);
      _enclosingClass = classElement;
    }
  
    @override
  