In the parse tree, combine LIMIT and OFFSET into a single expression rooted

on a TK_LIMIT node, for a small code size reduction and performance increase,
and a reduction in code complexity.

FossilOrigin-Name: 3925facd942c9df663f9b29b1e6f94f6be14af8c2b99eb691bfc836b4c220826

src/insert.c

@@ -2007,7 +2007,6 @@ static int xferOptimization(
   if( pSelect->pLimit ){
     return 0;   /* SELECT may not have a LIMIT clause */
   }
-  assert( pSelect->pOffset==0 );  /* Must be so if pLimit==0 */
   if( pSelect->pPrior ){
     return 0;   /* SELECT may not be a compound query */
   }