Merge pull request #12999 from Snuffleupagus/LoopbackPort-rm-sync

[api-minor] Remove support for synchronous event dispatching in `LoopbackPort`

src/display/api.js

@@ -1624,9 +1624,8 @@ class PDFPageProxy {
 }
 
 class LoopbackPort {
-  constructor(defer = true) {
+  constructor() {
     this._listeners = [];
-    this._defer = defer;
     this._deferred = Promise.resolve(undefined);
   }
 
@@ -1670,7 +1669,7 @@ class LoopbackPort {
           continue;
         }
         if (typeof desc.value === "function") {
-          if (value.hasOwnProperty && value.hasOwnProperty(i)) {
+          if (value.hasOwnProperty?.(i)) {
             throw new Error(
               `LoopbackPort.postMessage - cannot clone: ${value[i]}`
             );
@@ -1682,19 +1681,13 @@ class LoopbackPort {
       return result;
     }
 
-    if (!this._defer) {
-      this._listeners.forEach(listener => {
-        listener.call(this, { data: obj });
-      });
-      return;
-    }
-
     const cloned = new WeakMap();
-    const e = { data: cloneValue(obj) };
+    const event = { data: cloneValue(obj) };
+
     this._deferred.then(() => {
-      this._listeners.forEach(listener => {
-        listener.call(this, e);
-      });
+      for (const listener of this._listeners) {
+        listener.call(this, event);
+      }
     });
   }