1 files changed, 26 insertions, 11 deletions
diff --git a/dom/bindings/BindingUtils.cpp b/dom/bindings/BindingUtils.cpp
index 6c35da05e..4d20a95f7 100644
--- a/dom/bindings/BindingUtils.cpp
+++ b/dom/bindings/BindingUtils.cpp
@@ -3539,20 +3539,35 @@ CreateHTMLElement(const GlobalObject& aGlobal, const JS::CallArgs& aCallArgs,
 
   // Step 6 and Step 7 are in the code output by CGClassConstructor.
   // Step 8.
-  // Construction stack will be implemented in bug 1287348. So we always run
-  // "construction stack is empty" case for now.
-  RefPtr<nsGenericHTMLElement> element;
-  if (tag == eHTMLTag_userdefined) {
-    // Autonomous custom element.
-    element = NS_NewHTMLElement(nodeInfo.forget());
-  } else {
-    // Customized built-in element.
-    element = CreateHTMLElement(tag, nodeInfo.forget(), NOT_FROM_PARSER);
+  nsTArray<RefPtr<nsGenericHTMLElement>>& constructionStack =
+    definition->mConstructionStack;
+  if (constructionStack.IsEmpty()) {
+    RefPtr<nsGenericHTMLElement> newElement;
+    if (tag == eHTMLTag_userdefined) {
+      // Autonomous custom element.
+      newElement = NS_NewHTMLElement(nodeInfo.forget());
+    } else {
+      // Customized built-in element.
+      newElement = CreateHTMLElement(tag, nodeInfo.forget(), NOT_FROM_PARSER);
+    }
+
+    newElement->SetCustomElementData(
+      new CustomElementData(definition->mType, CustomElementData::State::eCustom));
+
+    return newElement.forget();
   }
 
-  element->SetCustomElementData(
-    new CustomElementData(definition->mType, CustomElementData::State::eCustom));
+  // Step 9.
+  RefPtr<nsGenericHTMLElement>& element = constructionStack.LastElement();
+
+  // Step 10.
+  if (element == ALEADY_CONSTRUCTED_MARKER) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return nullptr;
+  }
 
+  // Step 11 is in the code output by CGClassConstructor.
+  // Step 12 and Step 13.
   return element.forget();
 }