Implement statement parsing in the scanner. (#3137)

To implement let/const, the code affected by for statements needs to be identified,
and this patch implements the basic infrastructure for that. The short term benefit
is that scanner info blocks are not generated for do-while blocks.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

jerry-core/parser/js/js-parser-statm.c

@@ -697,11 +697,7 @@ parser_parse_do_while_statement_end (parser_context_t *context_p) /**< context *
 
   parser_set_continues_to_current_position (context_p, loop.branch_list_p);
 
-  /* FIXME: These statements should not have scanner info. */
-  if (context_p->next_scanner_info_p->type == SCANNER_TYPE_WHILE)
-  {
-    scanner_release_next (context_p, sizeof (scanner_location_info_t));
-  }
+  JERRY_ASSERT (context_p->next_scanner_info_p->source_p != context_p->source_p);
 
   parser_parse_enclosed_expr (context_p);