Restore visitLabelElement() and visitLocalVariableElement().

pkg/analyzer/lib/src/dart/element/element.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.src.dart.element.element;
 
 import 'dart:collection';
 import 'dart:math' show min;
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 5506 matching lines @@
 
   /**
    * Return `true` if this label is associated with a `switch` statement.
    */
   bool get isOnSwitchStatement => _onSwitchStatement;
 
   @override
   ElementKind get kind => ElementKind.LABEL;
 
   @override
-  T accept<T>(ElementVisitor<T> visitor) => throw new UnimplementedError();
+  T accept<T>(ElementVisitor<T> visitor) => visitor.visitLabelElement(this);
 }
 
 /**
  * A concrete implementation of a [LibraryElement].
  */
 class LibraryElementImpl extends ElementImpl implements LibraryElement {
   /**
    * The analysis context in which this library is defined.
    */
   final AnalysisContext context;
@@ skipping 781 matching lines @@
       return new SourceRange(
           _unlinkedVariable.visibleOffset, _unlinkedVariable.visibleLength);
     }
     if (_visibleRangeLength < 0) {
       return null;
     }
     return new SourceRange(_visibleRangeOffset, _visibleRangeLength);
   }
 
   @override
-  T accept<T>(ElementVisitor<T> visitor) => throw new UnimplementedError();
+  T accept<T>(ElementVisitor<T> visitor) =>
+      visitor.visitLocalVariableElement(this);
 
   @override
   void appendTo(StringBuffer buffer) {
     buffer.write(type);
     buffer.write(" ");
     buffer.write(displayName);
   }
 
   @override
   Declaration computeNode() => getNodeMatching(
@@ skipping 2537 matching lines @@
 
   @override
   DartObject computeConstantValue() => null;
 
   @override
   void visitChildren(ElementVisitor visitor) {
     super.visitChildren(visitor);
     _initializer?.accept(visitor);
   }
 }