Get rid of #source in pub.

utils/pub/entrypoint.dart

Index: utils/pub/entrypoint.dart
diff --git a/utils/pub/entrypoint.dart b/utils/pub/entrypoint.dart
index 86d586f01c52372a21dc4f0e0afefb5fde016ccc..855206830b47f7611f821ecd11c3e23ff08b050b 100644
--- a/utils/pub/entrypoint.dart
+++ b/utils/pub/entrypoint.dart
@@ -2,6 +2,14 @@
 // 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('entrypoint');
+
+#import('io.dart');
+#import('package.dart');
+#import('system_cache.dart');
+#import('version.dart');
+#import('utils.dart');
+
 /**
  * Pub operates over a directed graph of dependencies that starts at a root
  * "entrypoint" package. This is typically the package where the current