Migration of testing scripts in tools/ to libv2

tools/testing/dart/co19_test.dart

Index: tools/testing/dart/co19_test.dart
diff --git a/tools/testing/dart/co19_test.dart b/tools/testing/dart/co19_test.dart
index 4de996cad0a7247d1feaa08f4c14e7ce78740837..9a422e97bbfa464684920f43c2bb4f7ec53bda73 100644
--- a/tools/testing/dart/co19_test.dart
+++ b/tools/testing/dart/co19_test.dart
@@ -60,10 +60,10 @@ void main() {
   var verbose = firstConfiguration['verbose'];
   var listTests = firstConfiguration['list'];
 
-  var configurationIterator = configurations.iterator();
+  var configurationIterator = configurations.iterator;
   void enqueueConfiguration(ProcessQueue queue) {
-    if (!configurationIterator.hasNext) return;
-    var configuration = configurationIterator.next();
+    if (!configurationIterator.moveNext()) return;
+    var configuration = configurationIterator.current;
     for (String selector in selectors.keys) {
       if (selector == 'co19') {
         queue.addTestSuite(new Co19TestSuite(configuration));