LibWeb: Do not invert the dispatch_event result in fire_keyboard_event

The return value of fire_keyboard_event is meant to indicate whether the
event should continue propagating (true) or halt (false). This exactly
matches the return value of dispatch_event, so by negating the result,
we are propagating events we shouldn't, and not propagating events we
should.

Userland/Libraries/LibWeb/Page/EventHandler.cpp

@@ -712,16 +712,16 @@ bool EventHandler::fire_keyboard_event(FlyString const& event_name, HTML::Browsi
         }
 
         auto event = UIEvents::KeyboardEvent::create_from_platform_event(document->realm(), event_name, key, modifiers, code_point);
-        return !focused_element->dispatch_event(event);
+        return focused_element->dispatch_event(event);
     }
 
     // FIXME: De-duplicate this. This is just to prevent wasting a KeyboardEvent allocation when recursing into an (i)frame.
     auto event = UIEvents::KeyboardEvent::create_from_platform_event(document->realm(), event_name, key, modifiers, code_point);
 
     if (JS::GCPtr<HTML::HTMLElement> body = document->body())
-        return !body->dispatch_event(event);
+        return body->dispatch_event(event);
 
-    return !document->root().dispatch_event(event);
+    return document->root().dispatch_event(event);
 }
 
 bool EventHandler::handle_keydown(KeyCode key, unsigned modifiers, u32 code_point)