Cannot run incremental tests in checked mode, yet.

dart/tools/bots/compiler.py

 #!/usr/bin/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.
 
 """
 Dart2js buildbot steps
 
 Runs tests for the  dart2js compiler.
@@ skipping 252 matching lines @@
     p = subprocess.Popen(version_query_string,
         stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
     output, stderr = p.communicate()
     output = output.split()
     try:
       print 'Version of %s: %s' % (runtime, output[-1])
     except IndexError:
       # Failed to obtain version information. Continue running tests.
       pass
 
-  unit_test_flags = [flag for flag in flags if flag.startswith('--shard')]
-  # Run the unit tests in checked mode (the VM's checked mode).
-  unit_test_flags.append('--checked')
   if runtime == 'd8':
     # The dart2js compiler isn't self-hosted (yet) so we run its
     # unit tests on the VM. We avoid doing this on the builders
     # that run the browser tests to cut down on the cycle time.
+    unit_test_flags = [flag for flag in flags if flag.startswith('--shard')]
+    # Run the unit tests in checked mode (the VM's checked mode).
+    unit_test_flags.append('--checked')
     TestStep("dart2js_unit", mode, system, 'none', 'vm', ['dart2js', 'try'],
              unit_test_flags, arch)
 
   if compiler == 'dart2js' and runtime == 'drt':
+    unit_test_flags = [flag for flag in flags if flag.startswith('--shard')]
     # Ensure that we run the "try" tests on Content Shell.
     TestStep("incremental_compilation", mode, system, 'none', runtime,
              ['try'], unit_test_flags, arch)
 
   if compiler == 'dart2js' and runtime in ['ie10', 'ie11']:
     TestStep(compiler, mode, system, compiler, runtime,
              ['html', 'pkg', 'samples'], flags, arch)
   else:
     # Run the default set of test suites.
     TestStep(compiler, mode, system, compiler,
@@ skipping 111 matching lines @@
     if build_info.mode == 'debug':
       target = 'dart2js_bot_debug'
     args = [sys.executable, './tools/build.py', '--mode=' + build_info.mode,
             '--arch=' + build_info.arch, target]
     print 'Build SDK and d8: %s' % (' '.join(args))
     bot.RunProcess(args)
 
 
 if __name__ == '__main__':
   bot.RunBot(GetBuildInfo, RunCompilerTests, build_step=BuildCompiler)