[Evaluation] method calls and membership evaluation should be done on all factors, not just ID factors. The reason is that anonymous variables can also be de-referenced. For example, this is entirely legal (and useful):
[1,2,3].map(function(x) { return x + 1; });
"abc".length
Merge pull request #68 from ebirger/anon_vars_dereference

Method calls and membership evaluation should be done on all factors