dart2js cps: Support function types in 'is' and 'as' operators.

pkg/compiler/lib/src/js_backend/backend.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 js_backend;
 
 const VERBOSE_OPTIMIZER_HINTS = false;
 
 class JavaScriptItemCompilationContext extends ItemCompilationContext {
   final Set<HInstruction> boundsChecked = new Set<HInstruction>();
@@ skipping 1167 matching lines @@
 
   void registerClosureWithFreeTypeVariables(
       Element closure,
       Enqueuer enqueuer,
       Registry registry) {
     if (enqueuer.isResolutionQueue || methodNeedsRti(closure)) {
       registerComputeSignature(enqueuer, registry);
     }
   }
 
+  /// Call during codegen if an instance of [closure] is being created.
+  void registerInstantiatedClosure(LocalFunctionElement closure,
+                                   CodegenRegistry registry) {
+    if (methodNeedsRti(closure)) {
+      registerComputeSignature(compiler.enqueuer.codegen, registry);
+    }
+  }
+
   void registerBoundClosure(Enqueuer enqueuer) {
     boundClosureClass.ensureResolved(compiler);
     enqueuer.registerInstantiatedType(
         boundClosureClass.rawType,
         // Precise dependency is not important here.
         compiler.globalDependencies);
   }
 
   void registerGetOfStaticFunction(Enqueuer enqueuer) {
     closureClass.ensureResolved(compiler);
@@ skipping 1777 matching lines @@
   }
 }
 
 /// Records that [constant] is used by the element behind [registry].
 class Dependency {
   final ConstantValue constant;
   final Element annotatedElement;
 
   const Dependency(this.constant, this.annotatedElement);
 }