1 files changed, 21 insertions, 0 deletions
diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index c97d352872c..a61421e7866 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -36,6 +36,7 @@ use dom::bindings::xmlname::{namespace_from_domstring, validate_and_extract, xml
 use dom::bindings::xmlname::XMLName::InvalidXMLName;
 use dom::closeevent::CloseEvent;
 use dom::comment::Comment;
+use dom::customelementregistry::CustomElementDefinition;
 use dom::customevent::CustomEvent;
 use dom::documentfragment::DocumentFragment;
 use dom::documenttype::DocumentType;
@@ -1996,6 +1997,26 @@ impl Document {
 
         self.window.layout().nodes_from_point_response()
     }
+
+    /// https://html.spec.whatwg.org/multipage/#look-up-a-custom-element-definition
+    pub fn lookup_custom_element_definition(&self,
+                                            local_name: LocalName,
+                                            is: Option<LocalName>)
+                                            -> Option<Rc<CustomElementDefinition>> {
+        if !PREFS.get("dom.customelements.enabled").as_boolean().unwrap_or(false) {
+            return None;
+        }
+
+        // Step 2
+        if !self.has_browsing_context {
+            return None;
+        }
+
+        // Step 3
+        let registry = self.window.CustomElements();
+
+        registry.lookup_definition(local_name, is)
+    }
 }
 
 #[derive(PartialEq, HeapSizeOf)]