Only ClassElementImpl has TypeParameterizedElementMixin.

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

Index: pkg/analyzer/lib/src/dart/element/element.dart
diff --git a/pkg/analyzer/lib/src/dart/element/element.dart b/pkg/analyzer/lib/src/dart/element/element.dart
index 84eff00310724fda8ae87f290e4bf10d95374738..df85f1aa7f9e46f5a7c9b62d815db366fcf74ad4 100644
--- a/pkg/analyzer/lib/src/dart/element/element.dart
+++ b/pkg/analyzer/lib/src/dart/element/element.dart
@@ -35,7 +35,6 @@ import 'package:analyzer/src/task/dart.dart';
  * A concrete implementation of a [ClassElement].
  */
 abstract class AbstractClassElementImpl extends ElementImpl
-    with TypeParameterizedElementMixin
     implements ClassElement {
   /**
    * A list containing all of the accessors (getters and setters) contained in
@@ -49,13 +48,6 @@ abstract class AbstractClassElementImpl extends ElementImpl
   List<FieldElement> _fields = FieldElement.EMPTY_LIST;
 
   /**
-   * The superclass of the class, or `null` if the class does not have an
-   * explicit superclass.
-   */
-  @override
-  InterfaceType _supertype;
-
-  /**
    * The type defined by the class.
    */
   @override
@@ -96,9 +88,6 @@ abstract class AbstractClassElementImpl extends ElementImpl
   String get displayName => name;
 
   @override
-  TypeParameterizedElementMixin get enclosingTypeParameterContext => null;
-
-  @override
   List<FieldElement> get fields => _fields;
 
   /**
@@ -117,19 +106,6 @@ abstract class AbstractClassElementImpl extends ElementImpl
   @override
   ElementKind get kind => ElementKind.CLASS;
 
-  /**
-   * Return resynthesized type parameter elements.
-   */
-  List<TypeParameterElement> get resynthesizedTypeParameters {
-    return super.typeParameters;
-  }
-
-  @override
-  TypeParameterizedElementMixin get typeParameterContext => this;
-
-  @override
-  List<UnlinkedTypeParam> get unlinkedTypeParams => const <UnlinkedTypeParam>[];
-
   @override
   accept(ElementVisitor visitor) => visitor.visitClassElement(this);
 
@@ -445,7 +421,8 @@ class AuxiliaryElements {
 /**
  * An [AbstractClassElementImpl] which is a class.
  */
-class ClassElementImpl extends AbstractClassElementImpl {
+class ClassElementImpl extends AbstractClassElementImpl
+    with TypeParameterizedElementMixin {
   /**
    * The unlinked representation of the class in the summary.
    */
@@ -457,6 +434,11 @@ class ClassElementImpl extends AbstractClassElementImpl {
   List<TypeParameterElement> _typeParameters = TypeParameterElement.EMPTY_LIST;
 
   /**
+   * The superclass of the class, or `null` for [Object].
+   */
+  InterfaceType _supertype;
+
+  /**
    * A list containing all of the mixins that are applied to the class being
    * extended in order to derive the superclass of this class.
    */
@@ -629,6 +611,9 @@ class ClassElementImpl extends AbstractClassElementImpl {
   }
 
   @override
+  TypeParameterizedElementMixin get enclosingTypeParameterContext => null;
+
+  @override
   bool get hasNonFinalField {
     List<ClassElement> classesToVisit = new List<ClassElement>();
     HashSet<ClassElement> visitedClasses = new HashSet<ClassElement>();
@@ -848,9 +833,12 @@ class ClassElementImpl extends AbstractClassElementImpl {
   }
 
   @override
+  TypeParameterizedElementMixin get typeParameterContext => this;
+
+  @override
   List<TypeParameterElement> get typeParameters {
     if (_unlinkedClass != null) {
-      return resynthesizedTypeParameters;
+      return super.typeParameters;
     }
     return _typeParameters;
   }