Revert "Converting Polymer and TemplateElement to use deprecated Node.document"

sdk/lib/html/dartium/html_dartium.dart

Index: sdk/lib/html/dartium/html_dartium.dart
diff --git a/sdk/lib/html/dartium/html_dartium.dart b/sdk/lib/html/dartium/html_dartium.dart
index 6615ea2212b7b0045a2339b61838f994c7a47169..4e7a0f2f19fefd49029f32517c7016b3e668476c 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -25440,7 +25440,7 @@ class TemplateElement extends HtmlElement {
      }
 
     if (!isNative) {
-      var doc = _getTemplateContentsOwner(templateElement.document);
+      var doc = _getTemplateContentsOwner(templateElement.ownerDocument);
       templateElement._templateContent = doc.createDocumentFragment();
     }
 
@@ -25489,7 +25489,7 @@ class TemplateElement extends HtmlElement {
   //       + <td>Bar</td>
   //
   static Element _extractTemplateFromAttributeTemplate(Element el) {
-    var template = el.document.createElement('template');
+    var template = el.ownerDocument.createElement('template');
     el.parentNode.insertBefore(template, el);
 
     for (var name in el.attributes.keys.toList()) {