Change dart2js_foreign suite to use metadata.

dart/tests/compiler/dart2js_foreign/native_literal_class_test.dart

 // Copyright (c) 2012, 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.
 
-class A native "= {log: function() { return 42 } }" {
-  void log() native;
+@native("= {log: function() { return 42 } }")
+class A  {
+  @native void log();
 }
 
-getA() native """
+@native("""
   return A;
-""";
+""")
+getA();
 
 bar() {
   new A();
 }
 
 main() {
   var a = getA();
   // Make a call to bar to make sure A gets generated.
   if (a is int) bar();
   Expect.equals(42, a.log());
 }