fix #25740 again, making sure we have the substituted bound in inference

pkg/analyzer/lib/src/dart/element/member.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.member;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/constant/value.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
@@ skipping 919 matching lines @@
  *
  * If we have `C<num>.m` and we ask for the type parameter "S", we should get
  * `<S extends num>` instead of `<S extends T>`. This is how the parameter
  * and return types work, see: [FunctionType.parameters],
  * [FunctionType.returnType], and [ParameterMember].
  */
 class TypeParameterMember extends Member implements TypeParameterElement {
   @override
   final DartType bound;
 
+  DartType _type;
+
   TypeParameterMember(
       TypeParameterElement baseElement, DartType definingType, this.bound)
-      : super(baseElement, definingType);
+      : super(baseElement, definingType) {
+    _type = new TypeParameterTypeImpl(this);
+  }
 
   @override
   TypeParameterElement get baseElement =>
       super.baseElement as TypeParameterElement;
 
   @override
   Element get enclosingElement => baseElement.enclosingElement;
 
   @override
-  TypeParameterType get type => baseElement.type;
+  TypeParameterType get type => _type;
 
   @override
   accept(ElementVisitor visitor) => visitor.visitTypeParameterElement(this);
 
+  @override
+  int get hashCode => baseElement.hashCode;
+
+  @override
+  bool operator ==(obj) =>
+      // TODO(jmesserly): this equality should consider the bound, see:
+      // https://github.com/dart-lang/sdk/issues/27210
+      obj is TypeParameterMember && obj.baseElement == baseElement;
+
   /**
    * If the given [parameter]'s type is different when any type parameters from
    * the defining type's declaration are replaced with the actual type
    * arguments from the [definingType], create a parameter member representing
    * the given parameter. Return the member that was created, or the base
    * parameter if no member was created.
    */
   static TypeParameterElement from(
       TypeParameterElement parameter, ParameterizedType definingType) {
     if (parameter?.bound == null || definingType.typeArguments.isEmpty) {
@@ skipping 80 matching lines @@
   DartObject computeConstantValue() => baseElement.computeConstantValue();
 
   @override
   void visitChildren(ElementVisitor visitor) {
     // TODO(brianwilkerson) We need to finish implementing the accessors used
     // below so that we can safely invoke them.
     super.visitChildren(visitor);
     baseElement.initializer?.accept(visitor);
   }
 }