Don't set fastbuild=1 for Mac ASan trybots.

scripts/slave/recipe_modules/chromium/config.py

 # Copyright 2013 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 pipes
 
 from slave.recipe_config import config_item_context, ConfigGroup
 from slave.recipe_config import Dict, List, Single, Static, Set, BadConf
 from slave.recipe_config_types import Path
 
@@ skipping 355 matching lines @@
   c.compile_py.mode = 'official'
 
 @config_ctx(deps=['compiler'])
 def asan(c):
   if 'clang' not in c.compile_py.compiler:  # pragma: no cover
     raise BadConf('asan requires clang')
   c.runtests.lsan_suppressions_file = Path('[CHECKOUT]', 'tools', 'lsan',
                                            'suppressions.txt')
   if c.TARGET_PLATFORM == 'linux':
     c.gyp_env.GYP_DEFINES['use_allocator'] = 'none'
+  if c.TARGET_PLATFORM == 'mac':
+    # Set fastbuild=0 and prevent other configs from changing it.
+    fastbuild(c, invert=True, optional=False)
 
   c.gyp_env.GYP_DEFINES['asan'] = 1
   c.gyp_env.GYP_DEFINES['lsan'] = 1
 
 # TODO(infra,earthdok,glider): Make this a gyp variable. This is also not a
 # good name as only v8 builds release symbolized with -O2 while
 # chromium.lkgr uses -O1.
 @config_ctx()
 def asan_symbolized(c):
   c.gyp_env.GYP_DEFINES['release_extra_cflags'] = (
@@ skipping 300 matching lines @@
 def v8_verify_heap(c):
   c.gyp_env.GYP_DEFINES['v8_enable_verify_heap'] = 1
 
 @config_ctx()
 def chromium_perf(c):
   c.compile_py.clobber = False
 
 @config_ctx()
 def chromium_deterministic_build(c):
   c.gyp_env.GYP_DEFINES['dont_embed_build_metadata'] = 1