Implement part-of directive.

dart/tests/language/part2_test.dart

Index: dart/tests/language/part2_test.dart
diff --git a/dart/tests/language/extend_type_parameter_negative_test.dart b/dart/tests/language/part2_test.dart
similarity index 68%
copy from dart/tests/language/extend_type_parameter_negative_test.dart
copy to dart/tests/language/part2_test.dart
index 197447e62eaff533ffb3ba1139255084cab27738..f2e3bea63fedccbe3fadeca77379e653e2f7d5f4 100644
--- a/dart/tests/language/extend_type_parameter_negative_test.dart
+++ b/dart/tests/language/part2_test.dart
@@ -2,10 +2,10 @@
 // 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.
 
-// Extending a type parameter is not allowed.
+library org.dartlang.test.part2_test;
 
-class A<T> extends T { }
+part "part_part.dart"; // This is a static warning.
 
 main() {
-  A a = new A();
+  print(foo);
 }