Further reduce use of Compiler.closedWorld.

tests/compiler/dart2js/simple_inferrer_const_closure4_test.dart

Index: tests/compiler/dart2js/simple_inferrer_const_closure4_test.dart
diff --git a/tests/compiler/dart2js/simple_inferrer_const_closure4_test.dart b/tests/compiler/dart2js/simple_inferrer_const_closure4_test.dart
index eeeeb02606e58b032a3e5aec88c9fb6718d66749..2a2fd6260aafe1f8426cb12ed14f212cefabb2f4 100644
--- a/tests/compiler/dart2js/simple_inferrer_const_closure4_test.dart
+++ b/tests/compiler/dart2js/simple_inferrer_const_closure4_test.dart
@@ -30,6 +30,7 @@ void main() {
   var compiler = compilerFor(TEST, uri);
   asyncTest(() => compiler.run(uri).then((_) {
         var typesInferrer = compiler.globalInference.typesInferrerInternal;
+        var closedWorld = typesInferrer.closedWorld;
 
         checkArgument(String functionName, type) {
           var functionElement = findElement(compiler, functionName);
@@ -37,11 +38,11 @@ void main() {
           var element = signature.requiredParameters.first;
           Expect.equals(
               type,
-              simplify(typesInferrer.getTypeOfElement(element), compiler),
+              simplify(typesInferrer.getTypeOfElement(element), closedWorld),
               functionName);
         }
 
-        checkArgument('method', compiler.closedWorld.commonMasks.numType);
-        checkArgument('returnNum', compiler.closedWorld.commonMasks.numType);
+        checkArgument('method', closedWorld.commonMasks.numType);
+        checkArgument('returnNum', closedWorld.commonMasks.numType);
       }));
 }