Fix Immutable.d.ts typo
Fix Immutable.d.ts typo
maxehnert/immutable-js,facebook/immutable-js,facebook/immutable-js,maxehnert/immutable-js,facebook/immutable-js,donabrams/immutable-js,donabrams/immutable-js,maxehnert/immutable-js,maxehnert/immutable-js,facebook/immutable-js,donabrams/immutable-js