LibJS+LibWeb: Replace GlobalObject with Realm in object constructors

No functional changes - we can still very easily get to the global
object via `Realm::global_object()`. This is in preparation of moving
the intrinsics to the realm and no longer having to pass a global
object when allocating any object.
In a few (now, and many more in subsequent commits) places we get a
realm using `GlobalObject::associated_realm()`, this is intended to be
temporary. For example, create() functions will later receive the same
treatment and are passed a realm instead of a global object.

Userland/Libraries/LibJS/Module.cpp

@@ -97,7 +97,7 @@ Object* Module::module_namespace_create(VM& vm, Vector<FlyString> unambiguous_na
     // 6. Let sortedExports be a List whose elements are the elements of exports ordered as if an Array of the same values had been sorted using %Array.prototype.sort% using undefined as comparefn.
     // 7. Set M.[[Exports]] to sortedExports.
     // 8. Create own properties of M corresponding to the definitions in 28.3.
-    Object* module_namespace = vm.heap().allocate<ModuleNamespaceObject>(realm().global_object(), realm().global_object(), this, move(unambiguous_names));
+    Object* module_namespace = vm.heap().allocate<ModuleNamespaceObject>(realm().global_object(), realm(), this, move(unambiguous_names));
 
     // 9. Set module.[[Namespace]] to M.
     m_namespace = make_handle(module_namespace);