Minor performance improvement in deserializing lists
Minor performance improvement in deserializing lists

Some profiling on an earlier version of fitnesse revealed that there, a
nontrivial amount of CPU time was spent building the exceptions used to
communicate that the value of a list was not a sublist.

Probably not a huge deal as we're likely mostly IO-bound, but checking
beforehand can't hurt and makes the code a bit neater, too, IMHO.

rbevers/fitnesse,hansjoachim/fitnesse,amolenaar/fitnesse,hansjoachim/fitnesse,jdufner/fitnesse,rbevers/fitnesse,amolenaar/fitnesse,amolenaar/fitnesse,hansjoachim/fitnesse,jdufner/fitnesse,rbevers/fitnesse,jdufner/fitnesse