Add a new kind of suite to ease test.dart integration.

pkg/testing/lib/src/run.dart

Index: pkg/testing/lib/src/run.dart
diff --git a/pkg/testing/lib/src/run.dart b/pkg/testing/lib/src/run.dart
index d1d6d3ae653a2a8b3bede857f76b06debda4aa29..c6bf90271c2a795b245ff840b024043cd5f94e84 100644
--- a/pkg/testing/lib/src/run.dart
+++ b/pkg/testing/lib/src/run.dart
@@ -49,6 +49,9 @@ import 'suite.dart' show
     Dart,
     Suite;
 
+import 'test_dart.dart' show
+    TestDart;
+
 import 'zone_helper.dart' show
     acknowledgeControlMessages;
 
@@ -179,7 +182,16 @@ class SuiteRunner {
       suite.writeClosureOn(chain);
     }
 
-    if (testUris.isEmpty) return null;
+    bool hasTestDartSuite = false;
+    for (TestDart suite in suites.where((Suite suite) => suite is TestDart)) {
+      if (!hasTestDartSuite) {
+        suite.writeFirstImportOn(imports);
+      }
+      hasTestDartSuite = true;
+      suite.writeRunCommandOn(chain);
+    }
+
+    if (testUris.isEmpty && !hasTestDartSuite) return null;
 
     return """
 library testing.generated;