Mark img[loading] as supported in Firefox 75 (#5759)
Mark img[loading] as supported in Firefox 75 (#5759)

https://bugzilla.mozilla.org/show_bug.cgi?id=1542784 was closed as
Resolved: Fixed on 2020-02-12, with Target Milestone: mozilla75.
mdn/browser-compat-data,chrisdavidmills/browser-compat-data,chrisdavidmills/browser-compat-data,mdn/browser-compat-data