fix indexedMap by replacing base with from
fix indexedMap by replacing base with from

colinmccabe/core,ThomasWeiser/core,Pisys/core,Pisys/core,simonh1000/core,colinmccabe/core,martinos/core,rgrempel/core,ThomasWeiser/core,alexiamcdonald/elm-core,simonh1000/core,alexiamcdonald/elm-core,bradurani/core,martinos/core,rgrempel/core,bradurani/core