US regulators want a federal judge to break up Google to prevent the company from continuing to squash competition through its dominant search engine after a court found it had maintained an abusive monopoly over the past decade.   The proposed breakup floated in a 23-page document filed late Wednesday by the US Justice Department calls for Google to sell its industry-leading Chrome web browser and impose restrictions designed to prevent its Android smartphone software from favouring its search engine.   The recommended penalties underscore how severely regulators operating under President Joe Biden believe Google should be punished following an August ruling by US District Judge Amit Mehta that branded Google as a monopolist.