Report when members indirectly inherited through a mixin are not implemented (issue 26411)

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 440 matching lines @@
   }
 
   @override
   String get identifier => name;
 
   @override
   List<InterfaceType> get interfaces => _interfaces ??=
       _unlinkedClass.interfaces.map(_computeInterfaceType).toList();
 
   @override
+  bool get isMixinApplication => _unlinkedClass.isMixinApplication;
+
+  @override
   bool get isObject => _unlinkedClass.hasNoSupertype;
 
   @override
   LibraryElementForLink get library => enclosingElement.library;
 
   @override
   List<MethodElementForLink> get methods {
     if (_methods == null) {
       _methods = <MethodElementForLink>[];
       for (UnlinkedExecutable unlinkedExecutable
@@ skipping 4050 matching lines @@
    * there are no type parameters in scope.
    */
   TypeParameterizedElementForLink get _typeParameterContext;
 
   @override
   noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 
   @override
   String toString() => '$enclosingElement.$name';
 }