dart2js dart:html conversions for serialized script values.

tests/html/utils.dart

Index: tests/html/utils.dart
diff --git a/tests/html/utils.dart b/tests/html/utils.dart
index 7072f0c71473b3ade392429d8f3cd03cad0eb487..8b2dc9887cccd74bcd4c99d70a5f02f602d33215 100644
--- a/tests/html/utils.dart
+++ b/tests/html/utils.dart
@@ -21,7 +21,15 @@ verifyGraph(expected, actual) {
     // Cycle or DAG?
     for (int i = 0; i < eItems.length; i++) {
       if (expected === eItems[i]) {
-        Expect.identical(aItems[i], actual, message(path, 'back or side edge'));
+        Expect.identical(aItems[i], actual,
+                         message(path, 'missing back or side edge'));
+        return;
+      }
+    }
+    for (int i = 0; i < aItems.length; i++) {
+      if (actual === aItems[i]) {
+        Expect.identical(eItems[i], expected,
+                         message(path, 'extra back or side edge'));
         return;
       }
     }