The deregulation of the automobile insurance market in Massachusetts in 2008 had a pleasant side effect: lower premiums for homeowner policies, especially for consumers who bundled their auto and home insurance policies with the same compnay. But those gains are now in danger of blowing away. Citing the recent surge of tropical storms, tornadoes, and other weather-related events, insurers are asking the state to approve increases of 5 to 20 percent for homeowner insurance.