Feat: Add support for replaying :defined pseudo-class of custom elements (rrweb-io#1155)

* Feat: Add support for replaying :defined pseudo-class of custom elements

* add isCustom flag to serialized elements

Applying Justin's review suggestion

* fix code lint error

* add custom element event

* fix: tests (rrweb-io#1348)

* Update packages/rrweb/src/record/observer.ts

* Update packages/rrweb/src/record/observer.ts

---------

Co-authored-by: Nafees Nehar <[email protected]>
Co-authored-by: Justin Halsall <[email protected]>

Author: 3 people

packages/rrweb/src/record/iframe-manager.ts

@@ -271,7 +271,6 @@ export class IframeManager implements IframeManagerInterface {
         }
       }
     }
-
     return false;
   }
 

packages/rrweb/src/record/observer.ts

@@ -1242,12 +1242,8 @@ function initCustomElementObserver({
   customElementCb,
 }: observerParam): listenerHandler {
   const win = doc.defaultView as IWindow;
-  if (!win || !win.customElements) {
-    return () => {
-      // do nothing
-    };
-  }
-
+  // eslint-disable-next-line @typescript-eslint/no-empty-function
+  if (!win || !win.customElements) return () => {};
   const restoreHandler = patch(
     win.customElements,
     'define',