Change regression test now that String does have operator*.

tests/compiler/dart2js_extra/regress/4492_test.dart

Index: tests/compiler/dart2js_extra/regress/4492_test.dart
diff --git a/tests/compiler/dart2js_extra/regress/4492_test.dart b/tests/compiler/dart2js_extra/regress/4492_test.dart
index a80ae98457bad3d53f3e132843219245dab67925..2b3d6c8f608545d77dd4721d2bef987d962827fb 100644
--- a/tests/compiler/dart2js_extra/regress/4492_test.dart
+++ b/tests/compiler/dart2js_extra/regress/4492_test.dart
@@ -12,5 +12,6 @@ class A {
   }
 }
 
-main() => Expect.throws(() => new A().x(1, 2),
-                        (e) => e is NoSuchMethodError);
+main() {
+  Expect.throws(() => new A().x(1, 2));
+}