Change dart2js_foreign suite to use metadata.

dart/tests/compiler/dart2js_foreign/native_checked_fields_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.
 
 // Test that type checks occur on assignment to fields of native methods.
 
-class A native "*A" {
+@native("*A")
+class A  {
   int foo;
 }
 
-class B native "*B" {
+@native("*B")
+class B  {
   String foo;
 }
 
-A makeA() native { return new A(); }
-B makeB() native { return new B(); }
+@native A makeA() { return new A(); }
+@native B makeB() { return new B(); }
 
-void setup() native """
+@native("""
 function A() {}
 
 function B() {}
 
 makeA = function(){return new A;};
 makeB = function(){return new B;};
-""";
+""")
+void setup();
 
 expectThrows(action()) {
   bool threw = false;
   try {
     action();
   } catch (var e) {
     threw = true;
   }
   Expect.isTrue(threw);
 }
@@ skipping 67 matching lines @@
 
 main() {
   setup();
 
   if (isCheckedMode()) {
     checkedModeTest();
   } else {
     uncheckedModeTest();
   }
 }