LibWeb: Implement ReadableStream transfer

Author: https://github.com/trflynn89
Commit: 312db85a84
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4828
Reviewed-by: https://github.com/shannonbooth ✅

Libraries/LibWeb/HTML/StructuredSerialize.h

@@ -49,6 +49,7 @@ enum class TransferType : u8 {
     MessagePort = 1,
     ArrayBuffer = 2,
     ResizableArrayBuffer = 3,
+    ReadableStream = 4,
 };
 
 WebIDL::ExceptionOr<SerializationRecord> structured_serialize(JS::VM& vm, JS::Value);