Add --sky support in mojo_shell.py.

mojo/devtools/common/devtoolslib/http_server.py

 # 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.
 
 import atexit
 import datetime
 import email.utils
 import hashlib
 import logging
 import math
@@ skipping 122 matching lines @@
           SimpleHTTPServer.SimpleHTTPRequestHandler.translate_path(self, path))
 
       for prefix, local_base_path in mappings:
         if normalized_path.startswith(prefix):
           return os.path.join(local_base_path, normalized_path[len(prefix):])
 
       # This class is only used internally, and we're adding a catch-all ''
       # prefix at the end of |mappings|.
       assert False
 
+    def guess_type(self, path):
+      if path.endswith('.dart'):
+        return 'application/dart'
+      elif path.endswith('.sky'):
+        return 'text/sky'
+      return SimpleHTTPServer.SimpleHTTPRequestHandler.guess_type(self, path)
+
     def log_message(self, *_):
       """Override the base class method to disable logging."""
       pass
 
   RequestHandler.protocol_version = 'HTTP/1.1'
   return RequestHandler
 
 
 def StartHttpServer(local_dir_path, host_port=0, additional_mappings=None):
   """Starts an http server serving files from |local_dir_path| on |host_port|.
@@ skipping 15 matching lines @@
   mappings.append(('', local_dir_path))
   handler_class = _GetHandlerClassForPath(mappings)
 
   httpd = _SilentTCPServer(('127.0.0.1', host_port), handler_class)
   atexit.register(httpd.shutdown)
 
   http_thread = threading.Thread(target=httpd.serve_forever)
   http_thread.daemon = True
   http_thread.start()
   return httpd.server_address