Enable coredumps for dart2js unit tests on buildbot.

tools/bots/bot_utils.py

 #!/usr/bin/env python
 #
 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 import hashlib
 import imp
 import os
 import platform
 import string
 import subprocess
 import sys
 
+# The resource package does not exist on Windows but its functionality is not
+# used there, either.
+try:
+  import resource
+except ImportError:
+  resource = None;
+
 DART_DIR = os.path.abspath(
     os.path.normpath(os.path.join(__file__, '..', '..', '..')))
 
 def GetUtils():
   '''Dynamically load the tools/utils.py python module.'''
   return imp.load_source('utils', os.path.join(DART_DIR, 'tools', 'utils.py'))
 
 SYSTEM_RENAMES = {
   'win32': 'windows',
   'windows': 'windows',
@@ skipping 333 matching lines @@
 
   return checksum_filename
 
 def GetChannelFromName(name):
   """Get the channel from the name. Bleeding edge builders don't
       have a suffix."""
   channel_name = string.split(name, '-').pop()
   if channel_name in Channel.ALL_CHANNELS:
     return channel_name
   return Channel.BLEEDING_EDGE
+
+class CoredumpEnabler(object):
+  def __init__(self):
+    self._old_limits = None
+
+  def __enter__(self):
+    self._old_limits = resource.getrlimit(resource.RLIMIT_CORE)
+    resource.setrlimit(resource.RLIMIT_CORE, (-1, -1))
+
+  def __exit__(self, *_):
+    resource.setrlimit(resource.RLIMIT_CORE, self._old_limits)