GN: Reset default for fallback root certs to false.

tools/gn.py

 #!/usr/bin/env python
 # Copyright 2016 The Dart project 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 argparse
 import multiprocessing
 import os
 import subprocess
 import sys
@@ skipping 59 matching lines @@
 
   gn_args['dart_target_arch'] = arch
   gn_args['target_cpu'] = target_cpu_for_arch(arch, target_os)
   gn_args['host_cpu'] = host_cpu_for_arch(arch)
 
   # See: runtime/observatory/BUILD.gn.
   # This allows the standalone build of the observatory to fall back on
   # dart_bootstrap if the prebuilt SDK doesn't work.
   gn_args['dart_host_pub_exe'] = ""
 
+  # We only want the fallback root certs in the standalone VM on
+  # Linux and Windows.
+  if gn_args['target_os'] in ['linux', 'win']:
+    gn_args['dart_use_fallback_root_certificates'] = True
+
   gn_args['dart_zlib_path'] = "//runtime/bin/zlib"
 
   # Use tcmalloc only when targeting Linux and when not using ASAN.
   gn_args['dart_use_tcmalloc'] = (gn_args['target_os'] == 'linux'
                                   and not args.asan)
 
   # Force -mfloat-abi=hard and -mfpu=neon on Linux as we're specifying
   # a gnueabihf compiler in //build/toolchain/linux BUILD.gn.
   # TODO(zra): This will likely need some adjustment to build for armv6 etc.
   hard_float = (gn_args['target_cpu'].startswith('arm') and
@@ skipping 253 matching lines @@
       return 1
 
   endtime = time.time()
   if args.verbose:
     print ("GN Time: %.3f seconds" % (endtime - starttime))
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))