[ember] rewrite computed property unwrapping to use infer types
[ember] rewrite computed property unwrapping to use infer types

borisyankov/DefinitelyTyped,mcliment/DefinitelyTyped,borisyankov/DefinitelyTyped,georgemarshall/DefinitelyTyped,AgentME/DefinitelyTyped,markogresak/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,AgentME/DefinitelyTyped,georgemarshall/DefinitelyTyped,magny/DefinitelyTyped,AgentME/DefinitelyTyped,magny/DefinitelyTyped,AgentME/DefinitelyTyped