Remove incorrect save in splitter

According to this (https://github.com/D-Programming-Language/phobos/pull/1186#issuecomment-31254528) conversation with @andralex in regards to ranges "RoR" whose elements are themselves ranges "R", it is not "RoR" responsibility to save the *element* before returning them.

So I'm removing this save I added when I rewrote `splitter!pred`.

The other flavors of `splitter` don't have this problem, since they (currently) only support sliceable ranges...

@andralex or @AndrejMitrovic : This should be trivial and up your alley?