Kernel babysitter: track ExpMap into branches, too.
Kernel babysitter: track ExpMap into branches, too.

diku-dk/futhark,HIPERFIT/futhark,diku-dk/futhark,diku-dk/futhark,diku-dk/futhark,HIPERFIT/futhark,HIPERFIT/futhark,diku-dk/futhark