Ok, I thought Haiku avoid such multiprocess way as I found apps runs in one team generally.
At least I had not kill more teams but one, and then all related threads killed. if not I used Process Monitor to eliminate it.
I assumed WebKit2 would run this way,as I understood Zardshard’s explanations about 3 different processes, but I hoped its management would be solved until then that will be merged into Webpositive – to have seen Webpositive prosess, and more separate and adequately named NetworkPocess and WebProcess.