LibWeb: Implement DedicatedWorkerGlobalScope postMessage(msg, transfer)

Unfortunately the added test (which passes locally) is skipped as it is
based off other Worker tests which are also skipped due to being flakey
in CI.

Tests/LibWeb/TestConfig.ini

@@ -15,3 +15,4 @@ Text/input/Worker/Worker-importScripts.html
 Text/input/Worker/Worker-location.html
 Text/input/Worker/Worker-module.html
 Text/input/Worker/Worker-performance.html
+Text/input/Worker/Worker-postMessage-transfer.html

Tests/LibWeb/Text/expected/Worker/Worker-postMessage-transfer.txt

@@ -0,0 +1 @@
+Message received from worker: Hello, world

Tests/LibWeb/Text/input/Worker/Worker-postMessage-transfer.html

@@ -0,0 +1,29 @@
+<script src="../include.js"></script>
+<script>
+    asyncTest((done) => {
+        const workerScript = `
+            self.onmessage = function(evt) {
+                const receivedBuffer = evt.data;
+                self.postMessage(receivedBuffer, [receivedBuffer]);
+            };
+        `;
+
+        const blob = new Blob([workerScript], { type: 'application/javascript' });
+        const workerScriptURL = URL.createObjectURL(blob);
+        const worker = new Worker(workerScriptURL);
+
+        worker.onmessage = function(evt) {
+            const bufTransferredBackFromWorker = evt.data;
+            const decoder = new TextDecoder();
+
+            println('Message received from worker: ' + decoder.decode(bufTransferredBackFromWorker));
+            done();
+        };
+
+        const encoder = new TextEncoder();
+        const message = encoder.encode("Hello, world");
+        const myBuf = message.buffer;
+
+        worker.postMessage(myBuf, [myBuf]);
+    });
+</script>

Userland/Libraries/LibWeb/HTML/DedicatedWorkerGlobalScope.cpp

@@ -48,6 +48,7 @@ void DedicatedWorkerGlobalScope::finalize()
     WindowOrWorkerGlobalScopeMixin::finalize();
 }
 
+// https://html.spec.whatwg.org/multipage/workers.html#dom-dedicatedworkerglobalscope-postmessage-options
 WebIDL::ExceptionOr<void> DedicatedWorkerGlobalScope::post_message(JS::Value message, StructuredSerializeOptions const& options)
 {
     // The postMessage(message, transfer) and postMessage(message, options) methods on DedicatedWorkerGlobalScope objects act as if,
@@ -56,6 +57,15 @@ WebIDL::ExceptionOr<void> DedicatedWorkerGlobalScope::post_message(JS::Value mes
     return m_internal_port->post_message(message, options);
 }
 
+// https://html.spec.whatwg.org/multipage/workers.html#dom-dedicatedworkerglobalscope-postmessage
+WebIDL::ExceptionOr<void> DedicatedWorkerGlobalScope::post_message(JS::Value message, Vector<JS::Handle<JS::Object>> const& transfer)
+{
+    // The postMessage(message, transfer) and postMessage(message, options) methods on DedicatedWorkerGlobalScope objects act as if,
+    // when invoked, it immediately invoked the respective postMessage(message, transfer) and postMessage(message, options)
+    // on the port, with the same arguments, and returned the same return value.
+    return m_internal_port->post_message(message, transfer);
+}
+
 #undef __ENUMERATE
 #define __ENUMERATE(attribute_name, event_name)                                        \
     void DedicatedWorkerGlobalScope::set_##attribute_name(WebIDL::CallbackType* value) \

Userland/Libraries/LibWeb/HTML/DedicatedWorkerGlobalScope.h

@@ -26,6 +26,7 @@ public:
     virtual ~DedicatedWorkerGlobalScope() override;
 
     WebIDL::ExceptionOr<void> post_message(JS::Value message, StructuredSerializeOptions const&);
+    WebIDL::ExceptionOr<void> post_message(JS::Value message, Vector<JS::Handle<JS::Object>> const& transfer);
 
     void set_name(String name) { m_name = move(name); }
     String name() const { return m_name; }

Userland/Libraries/LibWeb/HTML/DedicatedWorkerGlobalScope.idl

@@ -5,8 +5,7 @@
 interface DedicatedWorkerGlobalScope : WorkerGlobalScope {
     [Replaceable] readonly attribute DOMString name;
 
-    // FIXME: IDL overload issue here
+    undefined postMessage(any message, sequence<object> transfer);
-    // FIXME: undefined postMessage(any message, sequence<object> transfer);
     undefined postMessage(any message, optional StructuredSerializeOptions options = {});
     undefined close();