LibJS+LibWeb: Replace GlobalObject with Realm in Heap::allocate<T>()

This is a continuation of the previous three commits.

Now that create() receives the allocating realm, we can simply forward
that to allocate(), which accounts for the majority of these changes.
Additionally, we can get rid of the realm_from_global_object() in one
place, with one more remaining in VM::throw_completion().

Userland/Libraries/LibWeb/HTML/Worker.cpp

@@ -110,7 +110,7 @@ void Worker::run_a_worker(AK::URL& url, EnvironmentSettingsObject& outside_setti
                 TODO();
             // FIXME: Make and use subclasses of WorkerGlobalScope, however this requires JS::GlobalObject to
             //        play nicely with the IDL interpreter, to make spec-compliant extensions, which it currently does not.
-            m_worker_scope = m_worker_vm->heap().allocate_without_global_object<JS::GlobalObject>(realm);
+            m_worker_scope = m_worker_vm->heap().allocate_without_realm<JS::GlobalObject>(realm);
             return m_worker_scope;
         },
         nullptr);