build: Add browserNoActivityTimeout to karma
build: Add browserNoActivityTimeout to karma

This reduces likeliness of tests failing. This exact change was used
for MediaWiki's karma run in March 2015; see T89075 for details.

Change-Id: I18205baf61495b503ec4cfad2accf1924a0d01c8

wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui