6826261: class file dumping from SA is broken Reviewed-by: kvn, jcoomes

6823453: DeoptimizeALot causes fastdebug server jvm to fail with assert(false,"unscheduable graph") Summary: Use a HaltNode on the fall through path of the AllocateArrayNode to indicate that it is unreachable if the array length is negative. Reviewed-by: never, jrose