Make dart recipes explicitly set GIT_MODE

scripts/slave/recipes/dart/dart2js_nobuild.py

 # Copyright 2016 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.
 
 DEPS = [
   'depot_tools/bot_update',
   'file',
   'depot_tools/gclient',
   'gsutil',
   'recipe_engine/path',
@@ skipping 72 matching lines @@
     shard = int(builder_fragments[-3])
     sharded = True
     options_end = - 3
   except ValueError:
     sharded = False
     options_end = - 1
   options = builder_fragments[3:options_end]
   for option in options:
     assert all_options.has_key(option)
 
-  api.gclient.set_config('dart')
+  api.gclient.set_config('dart', GIT_MODE=True)
   api.path.c.dynamic_paths['tools'] = None
   api.bot_update.ensure_checkout(force=True)
   api.path['tools'] = api.path['checkout'].join('tools')
   revision = api.properties['revision']
 
   api.gclient.runhooks()
 
   with api.step.defer_results():
     api.python('taskkill before building',
                api.path['checkout'].join('tools', 'task_kill.py'),
@@ skipping 113 matching lines @@
       api.properties.generic(
         mastername='client.dart',
         buildername='dart2js-linux-drt-93-105-dev',
         revision='hash_of_revision'))
    yield (
       api.test('dart2js-mac10.11-safari-1-3-be') + api.platform('mac', 64) +
       api.properties.generic(
         mastername='client.dart',
         buildername='dart2js-mac10.11-safari-1-3-be',
         revision='hash_of_revision'))