Rationalize Dart mojo and sky package structure

mojo/public/tools/dart_analyze.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.
 
 # To integrate dartanalyze with out build system, we take an input file, run
 # the analyzer on it, and write a stamp file if it passed.
 #
 # The first argument to this script is a reference to this build's gen
 # directory, which we treat as the package root. The second is the stamp file
@@ skipping 51 matching lines @@
     ]
 
     # Grab all the toplevel dart files in the archive.
     dart_files = glob.glob(os.path.join(temp_dir, "*.dart"))
 
     if not dart_files:
       return _success(stamp_file)
 
     cmd.extend(dart_files)
     cmd.extend(args)
-    cmd.append("--package-root=%s" % temp_dir)
+    cmd.append("--package-root=%s/packages" % temp_dir)
     cmd.append("--fatal-warnings")
 
     errors = 0
     try:
       subprocess.check_output(cmd, shell=False, stderr=subprocess.STDOUT)
     except subprocess.CalledProcessError as e:
       errors = set(l for l in e.output.split('\n')
                    if not any(p.match(l) for p in _IGNORED_PATTERNS))
       for error in sorted(errors):
         print >> sys.stderr, error.replace(temp_dir + "/", dartzip_basename)
 
     if not errors:
       return _success(stamp_file)
     return min(255, len(errors))
   finally:
     shutil.rmtree(temp_dir)
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))