Rationalize Dart mojo and sky package structure

mojo/public/tools/dart_list_packages_contents.py

 #!/usr/bin/python
 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """This script outputs the filenames of the files that are in the "packages/"
 subdir of the given directory, relative to that directory."""
 
 import argparse
 import os
 import sys
 
-def main(target_directory):
+def main(target_directory, package_name):
   os.chdir(target_directory)
+  self_path = 'packages/' + package_name
   for root, _, files in os.walk("packages", followlinks=True):
     for f in files:
-      print os.path.join(root, f)
+      path = os.path.join(root, f)
+      # Skip the contents of our own packages/package_name symlink.
+      if not path.startswith(self_path):
+        print os.path.join(root, f)
 
 if __name__ == '__main__':
   parser = argparse.ArgumentParser(
       description="List filenames of files in the packages/ subdir of the "
                   "given directory.")
   parser.add_argument("--target-directory",
                       dest="target_directory",
                       metavar="<target-directory>",
                       type=str,
                       required=True,
                       help="The target directory, specified relative to this "
                            "directory.")
+  parser.add_argument("--package-name",
+                      dest="package_name",
+                      metavar="<package-name>",
+                      type=str,
+                      required=True,
+                      help="The name of the package whose packages/ is being "
+                           "dumped.")
   args = parser.parse_args()
-  sys.exit(main(args.target_directory))
+  sys.exit(main(args.target_directory, args.package_name))