Reverting 30868 and 30873.

pkg/template_binding/lib/src/template.dart

Index: pkg/template_binding/lib/src/template.dart
diff --git a/pkg/template_binding/lib/src/template.dart b/pkg/template_binding/lib/src/template.dart
index 552c5cf3baa3fae3ae60d469bc327c7f15b6bdb4..ad35eb816beac4368f76a302765389a99d889966 100644
--- a/pkg/template_binding/lib/src/template.dart
+++ b/pkg/template_binding/lib/src/template.dart
@@ -17,8 +17,6 @@ class TemplateBindExtension extends _ElementExtension {
   DocumentFragment _content;
   bool _templateIsDecorated;
 
-  HtmlDocument _stagingDocument;
-
   var _bindingMap;
 
   TemplateBindExtension._(Element node) : super(node);
@@ -120,8 +118,9 @@ class TemplateBindExtension extends _ElementExtension {
       ref._bindingMap = map;
     }
 
-    var staging = _getTemplateStagingDocument();
-    var instance = _deepCloneIgnoreTemplateContent(content, staging);
+    var instance = map.hasSubTemplate
+        ? _deepCloneIgnoreTemplateContent(content)
+        : content.clone(true);
 
     _addMapBindings(instance, map, model, delegate, bound);
     // TODO(rafaelw): We can do this more lazily, but setting a sentinel
@@ -139,12 +138,12 @@ class TemplateBindExtension extends _ElementExtension {
     _ensureSetModelScheduled();
   }
 
-  static Node _deepCloneIgnoreTemplateContent(Node node, stagingDocument) {
-    var clone = stagingDocument.importNode(node, false);
+  static Node _deepCloneIgnoreTemplateContent(Node node) {
+    var clone = node.clone(false); // Shallow clone.
     if (isSemanticTemplate(clone)) return clone;
 
     for (var c = node.firstChild; c != null; c = c.nextNode) {
-      clone.append(_deepCloneIgnoreTemplateContent(c, stagingDocument));
+      clone.append(_deepCloneIgnoreTemplateContent(c));
     }
     return clone;
   }
@@ -242,7 +241,8 @@ class TemplateBindExtension extends _ElementExtension {
      }
 
     if (!isNative) {
-      var doc = _getOrCreateTemplateContentsOwner(templateElementExt._node);
+      var doc = _getTemplateContentsOwner(
+          templateElementExt._node.ownerDocument);
       templateElementExt._content = doc.createDocumentFragment();
     }
 
@@ -260,13 +260,12 @@ class TemplateBindExtension extends _ElementExtension {
   }
 
   static final _contentsOwner = new Expando();
-  static final _ownerStagingDocument = new Expando();
 
   // http://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/templates/index.html#dfn-template-contents-owner
-  static HtmlDocument _getOrCreateTemplateContentsOwner(Element template) {
-    var doc = template.ownerDocument;
-    if (doc.window == null) return doc;
-
+  static Document _getTemplateContentsOwner(HtmlDocument doc) {
+    if (doc.window == null) {
+      return doc;
+    }
     var d = _contentsOwner[doc];
     if (d == null) {
       // TODO(arv): This should either be a Document or HTMLDocument depending
@@ -280,19 +279,6 @@ class TemplateBindExtension extends _ElementExtension {
     return d;
   }
 
-  HtmlDocument _getTemplateStagingDocument() {
-    if (_stagingDocument == null) {
-      var owner = _node.ownerDocument;
-      var doc = _ownerStagingDocument[owner];
-      if (doc == null) {
-        doc = owner.implementation.createHtmlDocument('');
-        _ownerStagingDocument[owner] = doc;
-      }
-      _stagingDocument = doc;
-    }
-    return _stagingDocument;
-  }
-
   // For non-template browsers, the parser will disallow <template> in certain
   // locations, so we allow "attribute templates" which combine the template
   // element with the top-level container node of the content, e.g.