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

tools/dom/templates/html/impl/impl_Element.darttemplate

Index: tools/dom/templates/html/impl/impl_Element.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_Element.darttemplate b/tools/dom/templates/html/impl/impl_Element.darttemplate
index 305d5f2af341c748ea9f57842856cecff93c9be6..d319e0bb4cce45776157f85bc81fc6fa3b761e32 100644
--- a/tools/dom/templates/html/impl/impl_Element.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Element.darttemplate
@@ -830,7 +830,7 @@ $endif
   Element get ref {
     _ensureTemplate();
 
-    Element ref = null;
+    Element result = null;
     var refId = attributes['ref'];
     if (refId != null) {
       var treeScope = this;
@@ -844,11 +844,17 @@ $endif
           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;
   }
 
   /**