Sept 13 (Reuters) - Apple Inc’s shares stabilized on Monday after losing about $84 billion in market capitalization following a U.S. judge’s mixed decision on the iPhone maker’s fight with “Fortnite” game maker Epic Games last week. The court issued a permanent injunction that would let app developers to route its players to alternative platforms to make payments, allowing them to avoid Apple’s 30% App Store fees. Shares were up about 0.8% before the opening bell on Monday. They had closed down 3.3% on Friday.