Update prosemirror-state typings to 1.2
Update prosemirror-state typings to 1.2

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