SYDNEY, July 11 (Reuters) - An Australian court signed off on a A$450 million ($300 million) fine for Blackstone-owned (BX.N) casino operator Crown Resorts for breaking anti-money laundering laws, ending the darkest chapter in the company's history.The company, dominated by billionaire founder James Packer before he agreed to sell last year, agreed to the payment in May after allegations over wide-ranging governance problems sparked inquiries in all the states in which it operated, plus an investigation by the financial crime watchdog. read more But the fine needed the sign-off of the federal court, which approved the penalty, Australia's third-largest corporate fine, on Tuesday."The penal orders reflect the serious and unacceptable nature of the contraventions", judge Michael Lee said i...