Every open tab receives every push, and each one recounted every tag on
each Email change: two Email/query per tag, per account, for badges
nobody was looking at. Against a server where those queries are slow,
the rounds of several background tabs piled up behind each other.
A hidden tab now only notes the Email states it was told about and
recounts once when it becomes visible. On that return the client also
re-checks the server's states and replays them as a push when they moved
since its last check; a replay carrying exactly the states the return
recount already covered does not trigger a second one.
lucamzanon
17c6ab4ce0