V8: Run MB on staging bot.

scripts/slave/recipe_modules/v8/builders.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.
 
 # Contains the bulk of the V8 builder configurations so they can be reused
 # from multiple recipes.
 
 from recipe_engine.types import freeze
 from testing import V8NoExhaustiveVariants, V8Variant, V8VariantNeutral
 
@@ skipping 171 matching lines @@
             ['--extra-flags=--dead-code-elimination'],
             [V8Testing, Test262, Mozilla, SimdJs],
         ),
         'testing': {'platform': 'linux'},
         'enable_swarming': True,
         'swarming_dimensions': {
           'os': 'Ubuntu-12.04',
         },
       },
       'V8 Linux - swarming staging': {
-        'chromium_apply_config': ['clang', 'v8_ninja', 'goma', 'gn'],
+        'chromium_apply_config': ['clang', 'v8_ninja', 'goma', 'mb'],
         'v8_config_kwargs': {
           'BUILD_CONFIG': 'Release',
           'TARGET_BITS': 64,
         },
         'bot_type': 'builder_tester',
         'enable_swarming': True,
         'tests': [
           V8Initializers,
           V8Testing,
           OptimizeForSize,
@@ skipping 2324 matching lines @@
 dart_win_release['chromium_apply_config'].extend(['v8_ninja', 'msvs2013'])
 
 BUILDERS = freeze(BUILDERS)
 BRANCH_BUILDERS = freeze(BRANCH_BUILDERS)
 
 def iter_builders():
   for mastername, master_config in BUILDERS.iteritems():
     builders = master_config['builders']
     for buildername, bot_config in builders.iteritems():
       yield mastername, builders, buildername, bot_config