LibWeb: Make factory method of HTML::Navigator fallible

Userland/Libraries/LibWeb/HTML/Navigator.cpp

@@ -15,9 +15,9 @@
 
 namespace Web::HTML {
 
-JS::NonnullGCPtr<Navigator> Navigator::create(JS::Realm& realm)
+WebIDL::ExceptionOr<JS::NonnullGCPtr<Navigator>> Navigator::create(JS::Realm& realm)
 {
-    return realm.heap().allocate<Navigator>(realm, realm).release_allocated_value_but_fixme_should_propagate_errors();
+    return MUST_OR_THROW_OOM(realm.heap().allocate<Navigator>(realm, realm));
 }
 
 Navigator::Navigator(JS::Realm& realm)

Userland/Libraries/LibWeb/HTML/Navigator.h

@@ -22,7 +22,7 @@ class Navigator : public Bindings::PlatformObject
     WEB_PLATFORM_OBJECT(Navigator, Bindings::PlatformObject);
 
 public:
-    static JS::NonnullGCPtr<Navigator> create(JS::Realm&);
+    static WebIDL::ExceptionOr<JS::NonnullGCPtr<Navigator>> create(JS::Realm&);
 
     // FIXME: Implement NavigatorContentUtilsMixin