Extends native mixin tests.

tests/compiler/dart2js_native/native_mixin_test.dart

 // Copyright (c) 2013, 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 native classes can use ordinary Dart classes as mixins.
 
 class A native "*A" {
-  foo() => 42;
-  baz() => 99;
+  foo() => "A-foo";
+  baz() => "A-baz";
 }
 
 class B extends A with M native "*B" {
   bar() => baz();
 }
 
 class M {
-  foo() => 87;
-  bar() => 101;
+  foo() => "M-foo";
+  bar() => "M-bar";
 }
 
 A makeA() native;
 B makeB() native;
 
 void setup() native """
 function A() {}
 function B() {}
 makeA = function(){return new A;};
 makeB = function(){return new B;};
 """;
 
 main() {
   setup();
   A a = makeA();
-  Expect.equals(42, a.foo());
+  Expect.equals("A-foo", a.foo());
   Expect.throws(() => a.bar(), (error) => error is NoSuchMethodError);
-  Expect.equals(99, a.baz());
+  Expect.equals("A-baz", a.baz());
   Expect.isTrue(a is A);
   Expect.isFalse(a is B);
   Expect.isFalse(a is M);
 
   B b = makeB();
-  Expect.equals(87, b.foo());
-  Expect.equals(99, b.bar());
-  Expect.equals(99, b.baz());
+  Expect.equals("M-foo", b.foo());
+  Expect.equals("A-baz", b.bar());
+  Expect.equals("A-baz", b.baz());
   Expect.isTrue(b is A);
   Expect.isTrue(b is B);
   Expect.isTrue(b is M);
 
   M m = new M();
-  Expect.equals(87, m.foo());
-  Expect.equals(101, m.bar());
+  Expect.equals("M-foo", m.foo());
+  Expect.equals("M-bar", m.bar());
   Expect.throws(() => m.baz(), (error) => error is NoSuchMethodError);
   Expect.isFalse(m is A);
   Expect.isFalse(m is B);
   Expect.isTrue(m is M);
 }