Chrome delays throttling of tabs after user feedback

Follow up to https://news.ycombinator.com/item?id=13471543

Unfortunately, our current implementation throttles WebSockets. Because of this we ARE NOT SHIPPING this intervention in M56.

The current plan is to disable time-budget background timer throttling for the pages with active connection (websocket, webrtc and server-sent events) and to ship in M57 (subject to further feedback). We will keep you updated with the progress.