Put in a teardown for the docs test, fixed dom.py to actually run it correctly, added PRESUMBIT.

tools/dom/PRESUBMIT.py

+# Copyright (c) 2013, 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.
+
+"""
+Presubmit tests for dom tools.
+
+This file is run by git_cl or gcl when an upload or submit happens with
+any files at this level or lower are in the change list.
+
+See: http://www.chromium.org/developers/how-tos/depottools/presubmit-scripts
+"""
+
+
+import os
+
+
+def _AnySdkFiles(input_api):
+  """ Returns true if any of the changed files are in the sdk, meaning we should
+  check that docs.dart was run.
+  """
+  for f in input_api.change.AffectedFiles():
+    if f.LocalPath().find('sdk') > -1:
+      return True
+  return False
+
+
+def CheckChangeOnUpload(input_api, output_api):
+  results = []
+  # TODO(amouravski): uncomment this check once docs.dart is faster.
+  #  if _AnySdkFiles(input_api):
+  #    results.extend(CheckDocs(input_api, output_api))
+  return results
+
+
+def CheckChangeOnCommit(input_api, output_api):
+  results = []
+  if _AnySdkFiles(input_api):
+    results.extend(CheckDocs(input_api, output_api))
+  return results
+
+
+def CheckDocs(input_api, output_api):
+  """Ensure that documentation has been generated if it needs to be generated.
+
+  Prompts with a warning if documentation needs to be generated.
+  """
+  results = []
+
+  cmd = [os.path.join(input_api.PresubmitLocalPath(), 'dom.py'), 'test_docs']
+
+  try:
+    input_api.subprocess.check_output(cmd,
+                                      stderr=input_api.subprocess.STDOUT)
+  except (OSError, input_api.subprocess.CalledProcessError), e:
+    results.append(output_api.PresubmitPromptWarning(
+        ('Docs test failed!%s\nYou should run `dom.py docs`' % (
+            e if input_api.verbose else ''))))
+
+  return results