Fix Math.Truncate regression
Fix Math.Truncate regression

[tfs-changeset: 1560832]

tijoytom/corert,shrah/corert,mjp41/corert,botaberg/corert,manu-silicon/corert,schellap/corert,shrah/corert,gregkalapos/corert,shrah/corert,botaberg/corert,krytarowski/corert,sandreenko/corert,sandreenko/corert,gregkalapos/corert,kyulee1/corert,krytarowski/corert,manu-silicon/corert,mjp41/corert,sandreenko/corert,schellap/corert,schellap/corert,schellap/corert,gregkalapos/corert,krytarowski/corert,yizhang82/corert,sandreenko/corert,manu-silicon/corert,kyulee1/corert,yizhang82/corert,kyulee1/corert,yizhang82/corert,schellap/corert,manu-silicon/corert,kyulee1/corert,tijoytom/corert,tijoytom/corert,mjp41/corert,botaberg/corert,yizhang82/corert,krytarowski/corert,mjp41/corert,botaberg/corert,mjp41/corert,manu-silicon/corert,tijoytom/corert,gregkalapos/corert,shrah/corert