Mark ServiceWorkerContainer.startMessages as shipping in Chromium 74 (#3696)
Mark ServiceWorkerContainer.startMessages as shipping in Chromium 74 (#3696)

https://chromium.googlesource.com/chromium/src/+/1eef889053f1b30d62acccc34b1a3e66c5afd5e8
https://www.chromestatus.com/features/5751307839209472

There is no flag, so any Chromium-based browser will get this.
chrisdavidmills/browser-compat-data,mdn/browser-compat-data,chrisdavidmills/browser-compat-data,mdn/browser-compat-data