Adds a field to PerfomanceResourceTiming to indicate the HTTP response status when the resource was fetched.
Currently there is no straightforward way to tell if a resource failed loading for developers using the Resource Timing API. Indications exist for errored responses exists, but not for requests that got an error response. Exposing the status would enable analysis by segregation of resources based on the returned status. Analysis of 4xx and 5xx responses would be easier
Docs: https://github.com/w3c/resource-timing/blob/gh-pages/Explainers/Response_Status_Code.md