Support type variables as expressions.

sdk/lib/_internal/compiler/implementation/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;
 
 typedef void Recompile(Element element);
 
 class ReturnInfo {
   HType returnType;
@@ skipping 1050 matching lines @@
   }
 
   void registerRuntimeType(TreeElements elements) {
     enqueueInResolution(getSetRuntimeTypeInfo(), elements);
     enqueueInResolution(getGetRuntimeTypeInfo(), elements);
     enqueueInResolution(getGetRuntimeTypeArgument(), elements);
     compiler.enqueuer.resolution.registerInstantiatedClass(
         compiler.listClass, elements);
   }
 
+  void registerTypeVariableExpression(TreeElements elements) {
+    registerRuntimeType(elements);
+    enqueueInResolution(getRuntimeTypeToString(), elements);
+    enqueueInResolution(getCreateRuntimeType(), elements);
+  }
+
   void registerIsCheck(DartType type, Enqueuer world, TreeElements elements) {
     world.registerInstantiatedClass(compiler.boolClass, elements);
     bool isTypeVariable = type.kind == TypeKind.TYPE_VARIABLE;
     if (!type.isRaw || isTypeVariable) {
       enqueueInResolution(getSetRuntimeTypeInfo(), elements);
       enqueueInResolution(getGetRuntimeTypeInfo(), elements);
       enqueueInResolution(getGetRuntimeTypeArgument(), elements);
       enqueueInResolution(getCheckArguments(), elements);
       if (isTypeVariable) {
         enqueueInResolution(getGetObjectIsSubtype(), elements);
@@ skipping 451 matching lines @@
   }
 
   Element getGetRuntimeTypeInfo() {
     return compiler.findHelper(const SourceString('getRuntimeTypeInfo'));
   }
 
   Element getGetRuntimeTypeArgument() {
     return compiler.findHelper(const SourceString('getRuntimeTypeArgument'));
   }
 
+  Element getRuntimeTypeToString() {
+    return compiler.findHelper(const SourceString('runtimeTypeToString'));
+  }
+
   Element getCheckArguments() {
     return compiler.findHelper(const SourceString('checkArguments'));
   }
 
   Element getGetObjectIsSubtype() {
     return compiler.findHelper(const SourceString('objectIsSubtype'));
   }
 
   Element getThrowNoSuchMethod() {
     return compiler.findHelper(const SourceString('throwNoSuchMethod'));
@@ skipping 40 matching lines @@
   ClassElement get constListImplementation => jsArrayClass;
   ClassElement get fixedListImplementation => jsFixedArrayClass;
   ClassElement get growableListImplementation => jsExtendableArrayClass;
   ClassElement get mapImplementation => mapLiteralClass;
   ClassElement get constMapImplementation => constMapLiteralClass;
   ClassElement get functionImplementation => jsFunctionClass;
   ClassElement get typeImplementation => typeLiteralClass;
   ClassElement get boolImplementation => jsBoolClass;
   ClassElement get nullImplementation => jsNullClass;
 }