Make build incremental

tools/observatory_tool.py

 #!/usr/bin/env python
 # Copyright (c) 2015, 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.
 """Helper for building and deploying Observatory"""
 
 import argparse
 import os
 import shutil
 import subprocess
@@ skipping 78 matching lines @@
                               '--dart-executable=' + dart_executable,
                               'build',
                               '--output',
                               output_dir],
                               stdout=silent_sink if silent else None,
                               stderr=silent_sink if silent else None,)
 
 def Deploy(input_dir, output_dir):
   shutil.rmtree(output_dir)
   shutil.copytree(input_dir, output_dir, ignore=IGNORE_PATTERNS)
+  index_file = os.path.join(output_dir, 'web', 'index.html')
+  os.utime(index_file, None)
   return 0
 
 def RewritePubSpec(input_path, output_path, search, replace):
   with open(input_path, 'rb') as input_file:
     input_data = input_file.read()
     input_data = input_data.replace(search, replace)
     with open(output_path, 'wb+') as output_file:
       output_file.write(input_data)
 
 def ExecuteCommand(options, args):
@@ skipping 34 matching lines @@
   if (options.pub_executable != None):
     options.pub_executable = os.path.abspath(options.pub_executable)
   if len(args) == 1:
     args[0] = os.path.abspath(args[0])
   # Pub must be run from the project's root directory.
   ChangeDirectory(options.directory)
   return ExecuteCommand(options, args)
 
 if __name__ == '__main__':
   sys.exit(main());