Get rid of #source in pub.

utils/pub/source.dart

 // Copyright (c) 2012, 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('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.
  *
  * Each source has many packages that it looks up using [PackageId]s. The source
  * is responsible for installing these packages to the package cache.
  */
 class Source {
   /**
    * The name of the source. Should be lower-case, suitable for use in a
@@ skipping 38 matching lines @@
   /**
    * Returns a human-friendly name for the package identified by [id]. This
    * method should be light-weight. It doesn't need to validate that the given
    * package exists.
    *
    * The package name should be lower-case and suitable for use in a filename.
    * It may contain forward slashes.
    */
   String packageName(PackageId id) => id.description;
 }