1 files changed, 8 insertions, 0 deletions
diff --git a/dom/base/Element.cpp b/dom/base/Element.cpp
index 0054f48006..7d926f6bbc 100644
--- a/dom/base/Element.cpp
+++ b/dom/base/Element.cpp
@@ -4037,3 +4037,11 @@ Element::UpdateIntersectionObservation(DOMIntersectionObserver* aObserver, int32
   }
   return false;
 }
+
+void
+Element::SetCustomElementData(CustomElementData* aData)
+{
+  nsDOMSlots *slots = DOMSlots();
+  MOZ_ASSERT(!slots->mCustomElementData, "Custom element data may not be changed once set.");
+  slots->mCustomElementData = aData;
+}