Make dart recipes explicitly set GIT_MODE

scripts/slave/recipes/dart/dartium_build.py

 # Copyright 2014 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 = [
   'chromium',
   'depot_tools/gclient',
   'recipe_engine/path',
   'recipe_engine/platform',
   'recipe_engine/properties',
   'recipe_engine/python',
 ]
 
 def RunSteps(api):
   config_vals = {}
   config_vals.update(
     dict((str(k), v) for k, v in api.properties.iteritems() if k.isupper())
   )
 
   api.chromium.set_config('chromium', **config_vals)
-  api.gclient.set_config('chromium', **config_vals)
+  api.gclient.set_config('chromium', GIT_MODE=True, **config_vals)
 
   api.chromium.c.gyp_env.GYP_GENERATORS.add('ninja')
   api.chromium.c.gyp_env.GYP_DEFINES['linux_strip_binary'] = 1
 
   s = api.gclient.c.solutions[0]
 
   USE_MIRROR = api.gclient.c.USE_MIRROR
   def DartRepositoryURL(*pieces):
     BASES = ('https://dart.googlecode.com/svn',
              'svn://svn-mirror.golo.chromium.org/dart')
@@ skipping 30 matching lines @@
       for use_mirror in (True, False):
         yield (
           api.test('basic_%s_%s_Mirror%s' % (plat, bits, use_mirror)) +
           api.properties.generic(
               TARGET_BITS=bits,
               USE_MIRROR=use_mirror,
               deps='dartium.deps',
               revision='12345') +
           api.platform(plat, bits)
       )