re-enable pointer events inside platform views

Author: yjbanov

lib/web_ui/lib/src/engine/canvaskit/embedded_views.dart

@@ -223,6 +223,10 @@ class HtmlViewEmbedder {
     if (indexInFlutterView > -1) {
       skiaSceneHost!.children.insert(indexInFlutterView, head);
     }
+
+    // <flt-scene-host> disables pointer events. Reenable them here because the
+    // underlying platform view would want to handle the pointer events.
+    head.style.pointerEvents = 'auto';
     return head;
   }