Big merge from experimental to bleeding edge.

sdk/lib/html/html_common/lists.dart

Index: sdk/lib/html/html_common/lists.dart
diff --git a/sdk/lib/html/html_common/lists.dart b/sdk/lib/html/html_common/lists.dart
index 874039e05c399191c8ad71b4121c87cc844c9217..03cc29e5ccded15e85c4bd2d2a90906cdab186f5 100644
--- a/sdk/lib/html/html_common/lists.dart
+++ b/sdk/lib/html/html_common/lists.dart
@@ -66,4 +66,22 @@ class Lists {
     }
     return accumulator;
   }
+
+  static String join(List<Object> list, [String separator]) {
+    if (list.isEmpty) return "";
+    if (list.length == 1) return "${list[0]}";
+    StringBuffer buffer = new StringBuffer();
+    if (separator == null || separator == "") {
+      for (int i = 0; i < list.length; i++) {
+        buffer.add("${list[i]}");
+      }
+    } else {
+      buffer.add("${list[0]}");
+      for (int i = 1; i < list.length; i++) {
+        buffer.add(separator);
+        buffer.add("${list[i]}");
+      }
+    }
+    return buffer.toString();
+  }
 }