Stop running pub get at gclient sync time and fix build bugs

mojo/dart/dart_snapshotter/test/dart_snapshotter_test.py

 #!/usr/bin/env python
 # Copyright 2015 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 argparse
 import hashlib
 import os
 import subprocess
 import sys
 import tempfile
 
 SNAPSHOT_TEST_DIR = os.path.dirname(os.path.abspath(__file__))
 SRC_ROOT = os.path.dirname(os.path.dirname(os.path.dirname(os.path.dirname(
     SNAPSHOT_TEST_DIR))))
-DART_DIR = os.path.join(SRC_ROOT, 'dart')
+DART_DIR = os.path.join(SRC_ROOT, 'mojo', 'public', 'third_party', 'dart')
 
 VM_SNAPSHOT_FILES=[
   # Header files.
   'datastream.h',
   'object.h',
   'raw_object.h',
   'snapshot.h',
   'snapshot_ids.h',
   'symbols.h',
   # Source files.
@@ skipping 47 matching lines @@
     snapshot_file.seek(20)
     actual_hash = snapshot_file.read(32)
   if not actual_hash == expected_hash:
     print ('wrong hash: actual = %s, expected = %s'
            % (actual_hash, expected_hash))
     return 1
   return 0
 
 if __name__ == '__main__':
   sys.exit(main())