r14044 switched back from using a bit vector to distinguish field and literal values in the JTOC to using a hashmap. This is because the hashmaps have faster than O search times for an object, important for quick running benchmarks that spend a lot of their initial time loading and creating utf8 atoms. A downside to this is that reference fields cannot be easily flagged as literals at boot image write time. A problem arises at boot image write time as a JTOC slot represents a field, whereas the field itself is buried away somewhere in the host VM. If we try to force the field value into the JTOC at boot image write time then I find we get NPEs when the boot image is built with the opt compiler. Not having the literals flagged in the JTOC may mean we needlessly duplicate objects within the JTOC.