dart2js_native tests: Migrate 'native STRING' to JS-calls - part 2/2

tests/compiler/dart2js_native/fake_thing_test.dart

Index: tests/compiler/dart2js_native/fake_thing_test.dart
diff --git a/tests/compiler/dart2js_native/fake_thing_test.dart b/tests/compiler/dart2js_native/fake_thing_test.dart
index 6fd661bf38fcfbca30ea1e689014c9decf85bc44..2761a90497938734f05021832ecbb8e419c83d85 100644
--- a/tests/compiler/dart2js_native/fake_thing_test.dart
+++ b/tests/compiler/dart2js_native/fake_thing_test.dart
@@ -15,12 +15,15 @@ class Thing {}
 make1() native;
 make2() native;
 
-void setup() native r"""
-function A() {}
-A.prototype.$isThing = true;
-make1 = function(){return new A;};
-make2 = function(){return {$isThing: true}};
-""";
+void setup() {
+  JS('', r"""
+(function(){
+  function A() {}
+  A.prototype.$isThing = true;
+  make1 = function(){return new A;};
+  make2 = function(){return {$isThing: true}};
+})()""");
+}
 
 inscrutable(x) {
   if (new DateTime.now().millisecondsSinceEpoch == 0) {