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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 ecc640eeca3a073b08f2ba4456291cc962567b21..8e4757c36b6aa766d6aaee104fee6cc05387815a 100644
--- a/tools/dom/templates/html/impl/impl_Element.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Element.darttemplate
@@ -676,6 +676,7 @@ $endif
 
   bool _templateIsDecorated;
 
+
   /**
    * Gets the template this node refers to.
    * This is only supported if [isTemplate] is true.
@@ -687,7 +688,19 @@ $endif
     Element ref = null;
     var refId = attributes['ref'];
     if (refId != null) {
-      ref = document.getElementById(refId);
+      var treeScope = this;
+      while (treeScope.parentNode != null) {
+        treeScope = treeScope.parentNode;
+      }
+
+      // Note: JS code tests that getElementById is present. We can't do that
+      // easily, so instead check for the types known to implement it.
+      if (treeScope is Document ||
+          treeScope is ShadowRoot ||
+          treeScope is svg.SvgSvgElement) {
+
+        ref = treeScope.getElementById(refId);
+      }
     }
 
     return ref != null ? ref : _templateInstanceRef;
@@ -740,7 +753,8 @@ $endif
   };
 
   bool get _isAttributeTemplate => attributes.containsKey('template') &&
-      (localName == 'option' || _TABLE_TAGS.containsKey(localName));
+      (localName == 'option' || localName == 'optgroup' ||
+       _TABLE_TAGS.containsKey(localName));
 
   /**
    * Returns true if this node is a template.
@@ -749,7 +763,7 @@ $endif
    * 'template' attribute and this tag supports attribute form for backwards
    * compatibility with existing HTML parsers. The nodes that can use attribute
    * form are table elments (THEAD, TBODY, TFOOT, TH, TR, TD, CAPTION, COLGROUP
-   * and COL) and OPTION.
+   * and COL), OPTION, and OPTGROUP.
    */
   // TODO(jmesserly): this is not a public MDV API, but it seems like a useful
   // place to document which tags our polyfill considers to be templates.