Implement is-checks with typedefs for callable objects.

sdk/lib/_internal/compiler/implementation/ssa/optimize.dart

 // Copyright (c) 2012, 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.
 
 part of ssa;
 
 abstract class OptimizationPhase {
   String get name;
   void visitGraph(HGraph graph);
 }
@@ skipping 493 matching lines @@
     // If the intersection of the types is still the incoming type then
     // the incoming type was a subtype of the guarded type, and no check
     // is required.
     HType combinedType = types[value].intersection(node.guardedType, compiler);
     return (combinedType == types[value]) ? value : node;
   }
 
   HInstruction visitIs(HIs node) {
     DartType type = node.typeExpression;
     Element element = type.element;
-    if (identical(element.kind, ElementKind.TYPE_VARIABLE)) {
+    if (element.isTypeVariable()) {
       compiler.unimplemented("visitIs for type variables");
+    } if (element.isTypedef()) {
+      return node;
     }
 
     HType expressionType = types[node.expression];
     if (identical(element, compiler.objectClass)
         || identical(element, compiler.dynamicClass)) {
       return graph.addConstantBool(true, constantSystem);
     } else if (expressionType.isInteger()) {
       if (identical(element, compiler.intClass)
           || identical(element, compiler.numClass)
           || Elements.isNumberOrStringSupertype(element, compiler)) {
@@ skipping 951 matching lines @@
     HInstruction receiver = interceptor.receiver;
     for (var user in receiver.usedBy) {
       if (user is HInterceptor && interceptor.dominates(user)) {
         user.interceptedClasses = interceptor.interceptedClasses;
       }
     }
   }
 
   // TODO(ngeoffray): Also implement it for non-intercepted calls.
 }