Adjusts dart2js backend to handle method type arguments.

pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart

 // Copyright (c) 2013, 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.ir_builder;
 
 import '../closure.dart' as closure;
 import '../common.dart';
 import '../common/names.dart' show Selectors;
 import '../compile_time_constants.dart' show BackendConstantEnvironment;
@@ skipping 2716 matching lines @@
   /// Creates a type test or type cast of [value] against [type].
   ir.Primitive buildTypeOperator(
       ir.Primitive value, DartType type, SourceInformation sourceInformation,
       {bool isTypeTest}) {
     assert(isOpen);
     assert(isTypeTest != null);
 
     type = program.unaliasType(type);
 
     if (type.isMalformed) {
-      ErroneousElement element = type.element;
-      ir.Primitive message = buildStringConstant(element.message);
+      String message;
+      if (type is MalformedType) {
+        ErroneousElement element = type.element;
+        message = element.message;
+      } else {
+        assert(type is MethodTypeVariableType);
+        message = "Method type variables are not reified, "
+            "so they cannot be tested dynamically";
+      }
+      ir.Primitive irMessage = buildStringConstant(message);
       return buildStaticFunctionInvocation(program.throwTypeErrorHelper,
-          <ir.Primitive>[message], sourceInformation);
+          <ir.Primitive>[irMessage], sourceInformation);
     }
 
     List<ir.Primitive> typeArguments = const <ir.Primitive>[];
     if (type is GenericType && type.typeArguments.isNotEmpty) {
       typeArguments = type.typeArguments.map(buildTypeExpression).toList();
     } else if (type is TypeVariableType) {
       typeArguments = <ir.Primitive>[buildTypeVariableAccess(type)];
     } else if (type is FunctionType) {
       typeArguments = <ir.Primitive>[buildTypeExpression(type)];
     }
@@ skipping 159 matching lines @@
       this.sourceInformation});
 }
 
 class SwitchCaseInfo {
   final SubbuildFunction buildCondition;
   final SubbuildFunction buildBody;
   final SourceInformation sourceInformation;
 
   SwitchCaseInfo(this.buildCondition, this.buildBody, this.sourceInformation);
 }