Get the most basic mixin applications working.

tests/language/mixin_is_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.
+
+class S { }
+class M1 { }
+class M2 { }
+
+typedef C = S with M1;
+typedef D = S with M1, M2;
+typedef E = S with M2, M1;
+class F extends E { }
+
+typedef C_ = S with M1;
+typedef D_ = S with M1, M2;
+typedef E_ = S with M2, M1;
+class F_ extends E_ { }
+
+main() {
+  var c = new C();
+  Expect.isTrue(c is C);
+  Expect.isFalse(c is D);
+  Expect.isFalse(c is E);
+  Expect.isFalse(c is F);
+  Expect.isTrue(c is S);
+  Expect.isTrue(c is M1);
+  Expect.isFalse(c is M2);
+
+  var d = new D();
+  Expect.isFalse(d is C);
+  Expect.isTrue(d is D);
+  Expect.isFalse(d is E);
+  Expect.isFalse(d is F);
+  Expect.isTrue(d is S);
+  Expect.isTrue(d is M1);
+  Expect.isTrue(d is M2);
+
+  var e = new E();
+  Expect.isFalse(e is C);
+  Expect.isFalse(e is D);
+  Expect.isTrue(e is E);
+  Expect.isFalse(e is F);
+  Expect.isTrue(e is S);
+  Expect.isTrue(e is M1);
+  Expect.isTrue(e is M2);
+
+  var f = new F();
+  Expect.isFalse(f is C);
+  Expect.isFalse(f is D);
+  Expect.isTrue(f is E);
+  Expect.isTrue(f is F);
+  Expect.isTrue(f is S);
+  Expect.isTrue(f is M1);
+  Expect.isTrue(f is M2);
+
+  // Make sure we get a new class for each mixin
+  // application (at least the named ones).
+  Expect.isFalse(c is C_);
+  Expect.isFalse(c is D_);
+  Expect.isFalse(c is E_);
+  Expect.isFalse(c is F_);
+
+  Expect.isFalse(d is C_);
+  Expect.isFalse(d is D_);
+  Expect.isFalse(d is E_);
+  Expect.isFalse(d is F_);
+
+  Expect.isFalse(e is C_);
+  Expect.isFalse(e is D_);
+  Expect.isFalse(e is E_);
+  Expect.isFalse(e is F_);
+
+  Expect.isFalse(f is C_);
+  Expect.isFalse(f is D_);
+  Expect.isFalse(f is E_);
+  Expect.isFalse(f is F_);
+}