Do not set checked mode unconditionally for Dartium

tools/testing/architecture.py

 # Copyright (c) 2011, 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 os
 import platform
 import re
 import shutil
 import subprocess
@@ skipping 272 matching lines @@
       drt_location = os.path.abspath(drt_location)
     else:
       drt_location = os.path.join(self.root_path, 'client', 'tests', 'drt',
                                   'DumpRenderTree')
 
       # On Mac DumpRenderTree is a .app folder
       if platform.system() == 'Darwin':
         drt_location += '.app/Contents/MacOS/DumpRenderTree'
 
     drt_flags = ['--no-timeout']
-    dart_flags = '--dart-flags=--enable_asserts --enable_type_checks '
-    dart_flags += ' '.join(self.vm_options)
-
-    drt_flags.append(dart_flags)
+    if len(self.vm_options) > 0:
+      dart_flags = '--dart-flags='
+      dart_flags += ' '.join(self.vm_options)
+      drt_flags.append(dart_flags)
 
     html_output_file = os.path.join(self.GetHtmlPath(), self.GetHtmlName())
     f = open(html_output_file, 'w')
     f.write(self.GetHtmlContents())
     f.close()
 
     drt_flags.append(html_output_file)
 
     return [drt_location] + drt_flags
 
@@ skipping 289 matching lines @@
     return WebDriverArchitecture(root_path, arch, mode, component, test)
 
   elif component in ['vm', 'frog', 'frogsh']:
     return StandaloneArchitecture(root_path, arch, mode, component, test)
 
   elif component == 'leg':
     return LegArchitecture(root_path, arch, mode, component, test)
 
   elif component == 'dartc':
     return DartcArchitecture(root_path, arch, mode, component, test)