Implement 'displayName' for accessor and varaible elements in linker.

pkg/analyzer/lib/src/summary/link.dart

 // Copyright (c) 2016, 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.
 
 /**
  * This library is capable of producing linked summaries from unlinked
  * ones (or prelinked ones).  It functions by building a miniature
  * element model to represent the contents of the summaries, and then
  * scanning the element model to gather linked information and adding
  * it to the summary data structures.
@@ skipping 4333 matching lines @@
   @override
   ConstVariableNode get asConstVariable => variable._constNode;
 
   @override
   DartType get asStaticType => returnType;
 
   @override
   TypeInferenceNode get asTypeInferenceNode => variable._typeInferenceNode;
 
   @override
+  String get displayName => variable.displayName;
+
+  @override
   Element get enclosingElement => variable.enclosingElement;
 
   @override
   bool get isGetter => !isSetter;
 
   @override
   bool get isStatic => variable.isStatic;
 
   @override
   bool get isSynthetic => true;
@@ skipping 630 matching lines @@
   DartType get declaredType {
     if (unlinkedVariable.type == null) {
       return null;
     } else {
       return _declaredType ??= compilationUnit.resolveTypeRef(
           unlinkedVariable.type, _typeParameterContext);
     }
   }
 
   @override
+  String get displayName => unlinkedVariable.name;
+
+  @override
   PropertyAccessorElementForLink_Variable get getter =>
       _getter ??= new PropertyAccessorElementForLink_Variable(this, false);
 
   @override
   bool get hasImplicitType => unlinkedVariable.type == null;
 
   @override
   String get identifier => unlinkedVariable.name;
 
   /**
@@ skipping 76 matching lines @@
    * there are no type parameters in scope.
    */
   TypeParameterizedElementMixin get _typeParameterContext;
 
   @override
   noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 
   @override
   String toString() => '$enclosingElement.$name';
 }