LibWeb: Mark local variables captured in GC functions as ignored

These variables are all captured in queued events or other event loop
tasks, but are all guarded by event loop spins later in the function.

The IGNORE_USE_IN_ESCAPING_LAMBDA will soon be required for all locals
that are captured by ref in GC::Function as well as AK::Function.

Libraries/LibWeb/HTML/Scripting/Fetching.cpp

@@ -475,7 +475,7 @@ WebIDL::ExceptionOr<GC::Ref<ClassicScript>> fetch_a_classic_worker_imported_scri
     auto& vm = realm.vm();
 
     // 1. Let response be null.
-    GC::Ptr<Fetch::Infrastructure::Response> response = nullptr;
+    IGNORE_USE_IN_ESCAPING_LAMBDA GC::Ptr<Fetch::Infrastructure::Response> response = nullptr;
 
     // 2. Let bodyBytes be null.
     Fetch::Infrastructure::FetchAlgorithms::BodyBytes body_bytes;
@@ -510,6 +510,7 @@ WebIDL::ExceptionOr<GC::Ref<ClassicScript>> fetch_a_classic_worker_imported_scri
     }
 
     // 5. Pause until response is not null.
+    // FIXME: Consider using a "response holder" to avoid needing to annotate response as IGNORE_USE_IN_ESCAPING_LAMBDA.
     auto& event_loop = settings_object.responsible_event_loop();
     event_loop.spin_until(GC::create_function(vm.heap(), [&]() -> bool {
         return response;