Implement customElements.getName()

Fixes #3640.

Co-authored-by: Domenic Denicola <d@domenic.me>

Author: mash-graz

lib/jsdom/living/custom-elements/CustomElementRegistry-impl.js

@@ -227,6 +227,12 @@ class CustomElementRegistryImpl {
     return definition && definition.objectReference;
   }
 
+  // https://html.spec.whatwg.org/#dom-customelementregistry-getname
+  getName(constructor) {
+    const found = this._customElementDefinitions.find(entry => entry.objectReference === constructor.objectReference);
+    return found ? found.name : null;
+  }
+
   // https://html.spec.whatwg.org/#dom-customelementregistry-whendefined
   whenDefined(name) {
     if (!isValidCustomElementName(name)) {

lib/jsdom/living/custom-elements/CustomElementRegistry.webidl

@@ -2,6 +2,7 @@
 interface CustomElementRegistry {
   [CEReactions] undefined define(DOMString name, CustomElementConstructor constructor, optional ElementDefinitionOptions options = {});
   any get(DOMString name);
+  DOMString? getName(CustomElementConstructor constructor);
   Promise<void> whenDefined(DOMString name);
   [CEReactions] undefined upgrade(Node root);
 };

test/web-platform-tests/to-run.yaml

@@ -690,7 +690,6 @@ webkit-pseudo-element.html: [fail, Unknown]
 
 DIR: custom-elements
 
-CustomElementRegistry-getName.html: [fail, Unknown]
 CustomElementRegistry.html:
   "customElements.define must get \"observedAttributes\" property on the constructor prototype when \"attributeChangedCallback\" is present": [fail, Unknown]
   "customElements.define must get four additional callbacks on the prototype if formAssociated is converted to true": [fail, formAssociated not fully implemented]