Support runtime check of function types.

sdk/lib/_internal/compiler/implementation/js_backend/backend.dart

Index: sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart b/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
index 4f6add4feb2ccb5a4213cc3af8d96dc0199d4f29..d2deca13425e837804a05fbf84865bda00339131 100644
--- a/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
@@ -1070,6 +1070,13 @@ class JavaScriptBackend extends Backend {
     enqueueInResolution(getGetRuntimeTypeArgument(), elements);
   }
 
+  void registerGenericClosure(Enqueuer enqueuer, TreeElements elements) {
+    enqueue(enqueuer, getSetRuntimeTypeInfo(), elements);
+    enqueue(enqueuer, getGetRuntimeTypeInfo(), elements);
+    enqueue(enqueuer, getForwardRuntimeTypeInfo(), elements);
+    enqueuer.registerInstantiatedClass(compiler.listClass, elements);
+  }
+
   void registerRuntimeType(TreeElements elements) {
     enqueueInResolution(getSetRuntimeTypeInfo(), elements);
     enqueueInResolution(getGetRuntimeTypeInfo(), elements);
@@ -1085,9 +1092,13 @@ class JavaScriptBackend extends Backend {
   }
 
   void registerIsCheck(DartType type, Enqueuer world, TreeElements elements) {
+    if (type.isMalformed) {
+      registerThrowRuntimeError(elements);
+      return;
+    }
     world.registerInstantiatedClass(compiler.boolClass, elements);
     bool isTypeVariable = type.kind == TypeKind.TYPE_VARIABLE;
-    if (!type.isRaw || isTypeVariable) {
+    if (!type.isRaw || type.containsTypeVariables) {
       enqueueInResolution(getSetRuntimeTypeInfo(), elements);
       enqueueInResolution(getGetRuntimeTypeInfo(), elements);
       enqueueInResolution(getGetRuntimeTypeArgument(), elements);
@@ -1097,6 +1108,9 @@ class JavaScriptBackend extends Backend {
       }
       world.registerInstantiatedClass(compiler.listClass, elements);
     }
+    if (type is FunctionType) {
+      enqueueInResolution(getCheckFunctionSubtype(), elements);
+    }
     // [registerIsCheck] is also called for checked mode checks, so we
     // need to register checked mode helpers.
     if (compiler.enableTypeAssertions) {
@@ -1148,11 +1162,15 @@ class JavaScriptBackend extends Backend {
         compiler.listClass, elements);
   }
 
+  void enqueue(Enqueuer enqueuer, Element e, TreeElements elements) {
+    enqueuer.addToWorkList(e);
+    elements.registerDependency(e);
+  }
+
   void enqueueInResolution(Element e, TreeElements elements) {
     if (e == null) return;
     ResolutionEnqueuer enqueuer = compiler.enqueuer.resolution;
-    enqueuer.addToWorkList(e);
-    elements.registerDependency(e);
+    enqueue(enqueuer, e, elements);
   }
 
   void registerConstantMap(TreeElements elements) {
@@ -1547,6 +1565,10 @@ class JavaScriptBackend extends Backend {
     return compiler.findHelper(const SourceString('setRuntimeTypeInfo'));
   }
 
+  Element getForwardRuntimeTypeInfo() {
+    return compiler.findHelper(const SourceString('forwardRuntimeTypeInfo'));
+  }
+
   Element getGetRuntimeTypeInfo() {
     return compiler.findHelper(const SourceString('getRuntimeTypeInfo'));
   }
@@ -1567,6 +1589,10 @@ class JavaScriptBackend extends Backend {
     return compiler.findHelper(const SourceString('objectIsSubtype'));
   }
 
+  Element getCheckFunctionSubtype() {
+    return compiler.findHelper(const SourceString('checkFunctionSubtype'));
+  }
+
   Element getThrowNoSuchMethod() {
     return compiler.findHelper(const SourceString('throwNoSuchMethod'));
   }