dart2js_native tests: Migrate 'native STRING' to JS-calls

tests/compiler/dart2js_native/native_novel_html_test.dart

 // Copyright (c) 2011, 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.
 
 import 'native_testing.dart';
 
 // Test to see if novel HTML tags are interpreted as HTMLElement.
 
 @Native("HTMLElement")
 class Element {
   String dartMethod(int x) => 'dartMethod(${nativeMethod(x+1)})';
   String nativeMethod(int x) native;
 }
 
 makeE() native;
 makeF() native;
 
-void setup() native """
-// A novel HTML element.
-function HTMLGoofyElement(){}
-HTMLGoofyElement.prototype.nativeMethod = function(a) {
-  return 'Goofy.nativeMethod(' + a  + ')';
-};
-makeE = function(){return new HTMLGoofyElement};
+void setup() {
+  JS('', r"""
+(function(){
+  // A novel HTML element.
+  function HTMLGoofyElement(){}
+  HTMLGoofyElement.prototype.nativeMethod = function(a) {
+    return 'Goofy.nativeMethod(' + a  + ')';
+  };
+  makeE = function(){return new HTMLGoofyElement()};
 
-// A non-HTML element with a misleading name.
-function HTMLFakeyElement(){}
-HTMLFakeyElement.prototype.nativeMethod = function(a) {
-  return 'Fakey.nativeMethod(' + a  + ')';
-};
-makeF = function(){return new HTMLFakeyElement};
+  // A non-HTML element with a misleading name.
+  function HTMLFakeyElement(){}
+  HTMLFakeyElement.prototype.nativeMethod = function(a) {
+    return 'Fakey.nativeMethod(' + a  + ')';
+  };
+  makeF = function(){return new HTMLFakeyElement()};
 
-self.nativeConstructor(HTMLGoofyElement);
-""";
+  self.nativeConstructor(HTMLGoofyElement);
+})()""");
+}
 
 main() {
   nativeTesting();
   setup();
 
   var e = makeE();
   Expect.equals('Goofy.nativeMethod(10)', e.nativeMethod(10));
   Expect.equals('dartMethod(Goofy.nativeMethod(11))', e.dartMethod(10));
 
   var f = makeF();
   Expect.throws(() => f.nativeMethod(20), (e) => e is NoSuchMethodError,
       'fake HTML Element must not run Dart method on native class');
   Expect.throws(() => f.dartMethod(20), (e) => e is NoSuchMethodError,
       'fake HTML Element must not run native method on native class');
 }