Add a script to generate HTML and DOM docs with cross-links to one another.

utils/dartdoc/utils.dart

Index: utils/dartdoc/utils.dart
diff --git a/utils/dartdoc/utils.dart b/utils/dartdoc/utils.dart
index a77d5fcfeb6616681b2047964896368c8292c41c..b827772f84236076da2ae360a093b396d0cb679e 100644
--- a/utils/dartdoc/utils.dart
+++ b/utils/dartdoc/utils.dart
@@ -65,4 +65,15 @@ List orderByName(Map<String, Dynamic> map) {
     values.add(map[k]);
   }
   return values;
-}
+}
+
+/**
+ * Joins [items] into a single, comma-separated string using [conjunction].
+ * E.g. `['A', 'B', 'C']` becomes `"A, B, and C"`.
+ */
+String joinWithCommas(List<String> items, [String conjunction = 'and']) {
+  if (items.length == 1) return items[0];
+  if (items.length == 2) return "${items[0]} $conjunction ${items[1]}";
+  return Strings.join(items.getRange(0, items.length - 1), ', ') +
+    ', $conjunction ' + items[items.length - 1];
+}