[mdv] template.ref must recursive to find the original source template

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 2870931c48a5e8e8b2d82acc62f5573727bfa9d1..9e4bc063cd9d2dec6ec9fbe10b1cd176d7d4001a 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -8582,7 +8582,7 @@ abstract class Element extends Node implements ElementTraversal native "Element"
   Element get ref {
     _ensureTemplate();
 
-    Element ref = null;
+    Element result = null;
     var refId = attributes['ref'];
     if (refId != null) {
       var treeScope = this;
@@ -8596,11 +8596,17 @@ abstract class Element extends Node implements ElementTraversal native "Element"
           treeScope is ShadowRoot ||
           treeScope is svg.SvgSvgElement) {
 
-        ref = treeScope.getElementById(refId);
+        result = treeScope.getElementById(refId);
       }
     }
 
-    return ref != null ? ref : _templateInstanceRef;
+    if (result == null) {
+      result = _templateInstanceRef;
+      if (result == null) return this;
+    }
+
+    var nextRef = result.ref;
+    return nextRef != null ? nextRef : result;
   }
 
   /**