dart2js cps: Fix treatment of captured type variables.

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 '../compile_time_constants.dart' show
     BackendConstantEnvironment;
 import '../constants/constant_system.dart';
 import '../constants/values.dart' show
@@ skipping 2350 matching lines @@
                             SourceInformation sourceInformation) {
     ir.Primitive closure =
          buildFunctionExpression(classElement, sourceInformation);
     declareLocalVariable(functionElement, initialValue: closure);
   }
 
   ir.Primitive buildFunctionExpression(ClosureClassElement classElement,
                                        SourceInformation sourceInformation) {
     List<ir.Primitive> arguments = <ir.Primitive>[];
     for (ClosureFieldElement field in classElement.closureFields) {
-      // Captured 'this' is not available as a local in the current environment,
-      // so treat that specially.
-      ir.Primitive value = field.local is ThisLocal
-          ? buildThis()
-          : environment.lookup(field.local);
+      // Captured 'this' and type variables are not always available as locals
+      // in the environment, so treat those specially.
+      ir.Primitive value;
+      if (field.local is ThisLocal) {
+        value = buildThis();
+      } else if (field.local is TypeVariableLocal) {
+        TypeVariableLocal variable = field.local;
+        value = buildTypeVariableAccess(variable.typeVariable);
+      } else {
+        value = environment.lookup(field.local);
+      }
       arguments.add(value);
     }
     return addPrimitive(new ir.CreateInstance(
         classElement, arguments, const <ir.Primitive>[], sourceInformation));
   }
 
   /// Create a read access of [local] variable or parameter.
   ir.Primitive _buildLocalGet(LocalElement local) {
     assert(isOpen);
     ClosureLocation location = state.boxedVariables[local];
@@ skipping 409 matching lines @@
 }
 
 class SwitchCaseInfo {
   final List<ir.Primitive> constants = <ir.Primitive>[];
   final SubbuildFunction buildBody;
 
   SwitchCaseInfo(this.buildBody);
 
   void addConstant(ir.Primitive constant) => constants.add(constant);
 }