Count flushes to disable resize hack.

Instead of strictly using "first resize", also count flushes and
assume the hack isn't needed after five.  Experimentation on my
ChromeBook shows 3 to be sufficient, so I'm sing five for now.

Odds are that this will still mess with tiling WMs, but I don't use
one, so I don't mind yet.  I expect this will be better, but likely
still not great.