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

tests/compiler/dart2js_native/native_field_optimization_test.dart

 // Copyright (c) 2015, 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 that compiler is cautious with optimizations on native fields.  The
 // motivation is that DOM properties are getters and setters with arbitrary
 // effects.  Setting CSSStyleDeclaration.borderLeft can canonicalize the value
 // and changes the value of CSSStyleDeclaration.border.
 
 @Native("Foo")
 class Foo {
   var a;
   var b;
   var ab;
 }
 
 Foo makeFoo() native;
 
-void setup() native """
-function Foo() { this.i = 0; }
+void setup() {
+  JS('', r"""
+(function(){
+  function Foo() { this.i = 0; }
 
-Object.defineProperty(Foo.prototype, 'a', {
-  get: function () { return (this._a || '') + ++this.i; },
-  set: function (v) { this._a = v.toLowerCase(); }
-});
+  Object.defineProperty(Foo.prototype, 'a', {
+    get: function () { return (this._a || '') + ++this.i; },
+    set: function (v) { this._a = v.toLowerCase(); }
+  });
 
-Object.defineProperty(Foo.prototype, 'b', {
-  get: function () { return this._b || ''; },
-  set: function (v) { this._b = v.toLowerCase(); }
-});
+  Object.defineProperty(Foo.prototype, 'b', {
+    get: function () { return this._b || ''; },
+    set: function (v) { this._b = v.toLowerCase(); }
+  });
 
-Object.defineProperty(Foo.prototype, 'ab', {
-  get: function () { return this.a + ' ' + this.b; },
-  set: function (v) {
-    var s = v.split(' ');
-    this.a = s[0];
-    this.b = s[1];
-  }
-});
+  Object.defineProperty(Foo.prototype, 'ab', {
+    get: function () { return this.a + ' ' + this.b; },
+    set: function (v) {
+      var s = v.split(' ');
+      this.a = s[0];
+      this.b = s[1];
+    }
+  });
 
-makeFoo = function() { return new Foo() }
+  makeFoo = function() { return new Foo() };
 
-self.nativeConstructor(Foo);
-""";
+  self.nativeConstructor(Foo);
+})()""");
+}
 
 test1() {
   var f = makeFoo();
   f.a = 'Hi';
   f.b = 'There';
   Expect.equals('hi1 there', f.ab);
 }
 
 test2() {
   // Test for CSE. dart2js currently does CSE loads. Is this the right choice?
@@ skipping 28 matching lines @@
 }
 
 main() {
   nativeTesting();
   setup();
   (test1)();
   (test2)();
   (test3)();
   (test4)();
 }