Remove support for mixin typedefs in dart2js.

pkg/compiler/lib/src/resolution/class_hierarchy.dart

 // Copyright (c) 2015, 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 dart2js.resolution.class_hierarchy;
 
 import '../common.dart';
 import '../common/resolution.dart' show Resolution;
 import '../core_types.dart' show CoreClasses, CoreTypes;
 import '../dart_types.dart';
@@ skipping 258 matching lines @@
 
   DartType visitNamedMixinApplication(NamedMixinApplication node) {
     if (element == null) {
       throw reporter.internalError(node, 'element is null');
     }
     if (element.resolutionState != STATE_STARTED) {
       throw reporter.internalError(
           element, 'cyclic resolution of class $element');
     }
 
-    if (identical(node.classKeyword.stringValue, 'typedef')) {
-      // TODO(aprelev@gmail.com): Remove this deprecation diagnostic
-      // together with corresponding TODO in parser.dart.
-      reporter.reportWarningMessage(
-          node.classKeyword, MessageKind.DEPRECATED_TYPEDEF_MIXIN_SYNTAX);
-    }
-
     element.computeType(resolution);
     scope = new TypeDeclarationScope(scope, element);
     resolveTypeVariableBounds(node.typeParameters);
 
     // Generate anonymous mixin application elements for the
     // intermediate mixin applications (excluding the last).
     DartType supertype = resolveSupertype(element, node.superclass);
     Link<Node> link = node.mixins.nodes;
     while (!link.tail.isEmpty) {
       supertype = applyMixin(supertype, checkMixinType(link.head), link.head);
@@ skipping 349 matching lines @@
     Identifier selector = node.selector.asIdentifier();
     var e = prefixElement.lookupLocalMember(selector.source);
     if (e == null || !e.impliesType) {
       reporter.reportErrorMessage(node.selector,
           MessageKind.CANNOT_RESOLVE_TYPE, {'typeName': node.selector});
       return;
     }
     loadSupertype(e, node);
   }
 }