LibWeb: Set up the DefaultController when constructing a WritableStream

Author: https://github.com/mattco98
Commit: 0a220a19da
Pull-request: https://github.com/SerenityOS/serenity/pull/18266
Reviewed-by: https://github.com/linusg

Userland/Libraries/LibWeb/Streams/WritableStreamDefaultController.cpp

@@ -43,4 +43,9 @@ void WritableStreamDefaultController::error_steps()
     reset_queue(*this);
 }
 
+WritableStreamDefaultController::WritableStreamDefaultController(JS::Realm& realm)
+    : Bindings::PlatformObject(realm)
+{
+}
+
 }