Test for native class with factory constructors.

tests/language/src/NativeNamedConstructors1FrogTest.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.
+
+#library('X');
+#native('NativeNamedConstructors1FrogTest.js');  // Defines JS constructor 'A'.
+
+// The native class has several constructors which partition the behaviour of
+// the JS constructor function into several well-typed Dart constructors.
+
+class A native "A" {
+
+  // factory constructors allow us to do computation ahead of the allocation.
+  factory A(int len) { return _construct(len); }
+
+  factory A.fromString(String s) {
+    return _construct(s.length);  // convert string to int.
+  }
+
+  // Helper that does the actual allocation and construction.
+  static A _construct(v) native @'return new A(v);';
+
+  foo() native 'return this._x;';
+}
+
+main() {
+  var a1 = new A(100);
+  var a2 = new A.fromString('Hello');
+
+  Expect.equals(100, a1.foo());
+  Expect.equals(5, a2.foo());
+}