Get rid of #source in pub.

utils/pub/source.dart

Index: utils/pub/source.dart
diff --git a/utils/pub/source.dart b/utils/pub/source.dart
index 85e9c99a0acb33bb83570ba6bd6d7bcaf8c09787..974f677f31dd626a90a69ca326e70a27ed583cf7 100644
--- a/utils/pub/source.dart
+++ b/utils/pub/source.dart
@@ -2,15 +2,9 @@
 // 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('pub_source');
+#library('source');
 
-#import('io.dart');
-#import('pub.dart');
-#import('utils.dart');
-
-#source('git_source.dart');
-#source('sdk_source.dart');
-#source('source_registry.dart');
+#import('package.dart');
 
 /**
  * A source from which to install packages.