Further reduce use of Compiler.closedWorld.

tests/compiler/dart2js/list_tracer2_test.dart

Index: tests/compiler/dart2js/list_tracer2_test.dart
diff --git a/tests/compiler/dart2js/list_tracer2_test.dart b/tests/compiler/dart2js/list_tracer2_test.dart
index c0a5166599f5eb1136eea0345d2a07b23ca4cdbc..215b84a98cfa2d4f878453aaec2be3c9fd30ae3c 100644
--- a/tests/compiler/dart2js/list_tracer2_test.dart
+++ b/tests/compiler/dart2js/list_tracer2_test.dart
@@ -25,13 +25,14 @@ void main() {
   var compiler = compilerFor(TEST, uri);
   asyncTest(() => compiler.run(uri).then((_) {
         var typesInferrer = compiler.globalInference.typesInferrerInternal;
+        var closedWorld = typesInferrer.closedWorld;
 
         checkType(String name, type) {
           var element = findElement(compiler, name);
           ContainerTypeMask mask = typesInferrer.getTypeOfElement(element);
-          Expect.equals(type, simplify(mask.elementType, compiler), name);
+          Expect.equals(type, simplify(mask.elementType, closedWorld), name);
         }
 
-        checkType('myList', compiler.closedWorld.commonMasks.uint31Type);
+        checkType('myList', typesInferrer.closedWorld.commonMasks.uint31Type);
       }));
 }