Properly namespace ignore_patterns in remove_html_imports.

tools/remove_html_imports.py

 #!/usr/bin/env python
 # Copyright (c) 2014, 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.
 
 '''Tool for removing dart:html and related imports from a library.
 
 Copy SOURCE to TARGET, removing any lines that import dart:html.
 
 Usage:
   python tools/remove_html_imports.py SOURCE TARGET
 '''
 
 import os
 import re
 import shutil
 import sys
 
 HTML_IMPORT = re.compile(r'''^import ["']dart:(html|html_common|indexed_db'''
                          r'''|js|svg|web_(audio|gl|sql))["'];$''',
                          flags=re.MULTILINE)
 
 def main(argv):
   source = argv[1]
   target = argv[2]
   shutil.rmtree(target)
-  shutil.copytree(source, target, ignore=ignore_patterns('.svn'))
+  shutil.copytree(source, target, ignore=shutil.ignore_patterns('.svn'))
 
   for root, subFolders, files in os.walk(target):
     for path in files:
       if not path.endswith('.dart'): next
       with open(os.path.join(root, path), 'r+') as f:
         contents = f.read()
         f.seek(0)
         f.truncate()
         f.write(HTML_IMPORT.sub(r'// import "dart:\1";', contents))
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))