Fix parsing of factory calls (issue 500).

tests/language/src/Factory2Test.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.
+// Dart test program for testing factories.
+
+interface Link<T> extends Iterable<T> factory LinkFactory {
+  Link(T head, [Link<T> tail]);
+  Link<T> prepend(T element);
+}
+
+interface EmptyLink<T> extends Link<T> factory LinkTail<T> {
+  const EmptyLink();
+}
+
+class LinkFactory {
+  factory Link<T>(head, [Link tail]) {
+  }
+}
+
+class AbstractLink<T> implements Link<T> {
+  const AbstractLink();
+  Link<T> prepend(T element) {
+    return new Link<T>(element, this);
+  }
+}
+
+class LinkTail<T> extends AbstractLink<T> implements EmptyLink<T> {
+  const LinkTail();
+}
+
+class LinkEntry<T> extends AbstractLink<T> {
+  LinkEntry(T head, Link<T> realTail);
+}
+
+class Fisk {
+ Link<String> nodes = const EmptyLink();
+}
+
+main() {
+  new Fisk();
+  new EmptyLink<String>().prepend('hest');
+  const EmptyLink<String>().prepend('fisk');
+}
+