Removed a comment. Memoization of trivial calls do not seem effective.

src/Coverage.ml

@@ -544,10 +544,6 @@ let () =
 (* TEMPORARY implement and exploit [Lr1.ImperativeNodeMap] using an array *)
 (* TEMPORARY the code in this module should run only if --coverage is set *)
 (* TEMPORARY gain a constant factor by memoizing [nullable_first_prod]? *)
-(* TEMPORARY gain some time and space by not memoizing "trivial" calls
-             e.g. when n = 0
-             e.g. when there is just one recursive call with i+1
-*)
 (* TEMPORARY maybe cutoff didn't work because productions were not sorted by length? *)
 (* TEMPORARY key idea? stop searching as soon as the lower bound predicted by [MINIMAL]
              is reached *)