Implement modular compilation

test/samples/runtimetypechecktest.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.
-
-library runtimetypechecktest;
-
-class A<T> {
-  T x;
-  A(this.x);
-
-  isT(t) => t is T;
-}
-
-class B extends A<int> {
-  B(int x) : super(x);
-}
-
-int foo(B b) => b.x;
-
-typedef int Foo(B b);
-
-void main() {
-  var a = new B(42);
-  print(a is A);
-  print(a as A);
-  print(a is B);
-  print(a as B);
-  print(a is A<int>);
-  print(a as A<int>);
-  print(foo is Foo);
-  print(a is dynamic);
-  print(a as dynamic);
-}