test.py: Propagate the global --dartium option to the browser controller

tools/testing/dart/test_runner.dart

Index: tools/testing/dart/test_runner.dart
diff --git a/tools/testing/dart/test_runner.dart b/tools/testing/dart/test_runner.dart
index cb9de965995f306e38660440e7db8d2679ac0b84..3b2c85d9fa29bc8fb8e68fccec3361eff76b168c 100644
--- a/tools/testing/dart/test_runner.dart
+++ b/tools/testing/dart/test_runner.dart
@@ -2077,7 +2077,8 @@ class CommandExecutorImpl implements CommandExecutor {
     var num_browsers = maxBrowserProcesses;
     if (_browserTestRunners[browser] == null) {
       var testRunner =
-        new BrowserTestRunner(local_ip, browser, num_browsers);
+        new BrowserTestRunner(
+            globalConfiguration, local_ip, browser, num_browsers);
       if (globalConfiguration['verbose']) {
         testRunner.logger = DebugLogger.info;
       }