5d41ea2cd4
There was an update to LCP spec such that the `renderTime` is no longer protected by Timing-Allow-Origin due to it's easy to side channel attack it and it isn't needed for CORS protected images. The solution was to coarsen the timestamp by 4ms (this is what Chrome did). To do something similar in Firefox, we don't need to coarsen the timestamp because we already reduce more precisions. We just need to always expose this. Spec discussion: https://github.com/w3c/largest-contentful-paint/issues/111 Differential Revision: https://phabricator.services.mozilla.com/D247492