jscript: Get rid of instr_off from expression_t.

dlls/jscript/engine.h

@@ -481,7 +481,6 @@ typedef enum {
 
 struct _expression_t {
     expression_type_t type;
-    unsigned instr_off;
 };
 
 struct _parameter_t {

dlls/jscript/parser.y

@@ -1342,7 +1342,6 @@ static void *new_expression(parser_ctx_t *ctx, expression_type_t type, size_t si
     expression_t *ret = parser_alloc(ctx, size ? size : sizeof(*ret));
 
     ret->type = type;
-    ret->instr_off = 0;
 
     return ret;
 }