Basic support for dev_compiler in test.dart.

tools/testing/dart/browser_controller.dart

 // 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.
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:core';
 import 'dart:io';
 import 'dart:math';
 
@@ skipping 484 matching lines @@
               }
             });
           }
         };
         var args = [
           "--user-data-dir=${userDir.path}",
           url,
           "--disable-extensions",
           "--disable-popup-blocking",
           "--bwsi",
-          "--no-first-run"
+          "--no-first-run",
         ];
+
+        // TODO(rnystrom): Uncomment this to open the dev tools tab when Chrome

[Bill Hesse, 2017/06/21 16:33:20]

Commented code is disallowed, I think.  You could write it not as code, but as a
pure comment.

[Bob Nystrom, 2017/06/21 20:18:28]

Done.

+        // is spawned. Handy for debugging tests.
+        // args.add("--auto-open-devtools-for-tabs");
+
         return startBrowserProcess(_binary, args,
             environment: _getEnvironment());
       });
     }).catchError((e) {
       _logEvent("Running $_binary --version failed with $e");
       return false;
     });
   }
 
   String toString() => "Chrome";
@@ skipping 1423 matching lines @@
           'exit code: ${result.exitCode}\n'
           'stdout: ${result.stdout}\n'
           'stderr: ${result.stderr}');
     } else {
       print('[$message] Successfully uploaded screenshot to $storageUrl');
     }
     new File(screenshotFile).deleteSync();
   }
   print('--------------------------------------------------------------------');
 }