Do not set checked mode unconditionally for Dartium

tools/testing/dart/test_suite.dart

Index: tools/testing/dart/test_suite.dart
diff --git a/tools/testing/dart/test_suite.dart b/tools/testing/dart/test_suite.dart
index 3bb4fdf8cebb298f83ceb00ba667812776436008..74c4297d0c67aa4d800bc3ccefcc59667d69cf0a 100644
--- a/tools/testing/dart/test_suite.dart
+++ b/tools/testing/dart/test_suite.dart
@@ -467,9 +467,11 @@ class StandardTestSuite implements TestSuite {
       } else {
         args = ['--no-timeout'];
         if (component == 'dartium') {
-          var dartFlags = ['--enable_asserts',
-                           '--enable_type_checks',
-                           '--ignore-unrecognized-flags'];
+          var dartFlags = ['--ignore-unrecognized-flags'];
+          if (configuration["checked"]) {
+            dartFlags.add('--enable_asserts');
+            dartFlags.add("--enable_type_checks");
+          }
           dartFlags.addAll(vmOptions);
           args.add('--dart-flags=${Strings.join(dartFlags, " ")}');
         }