parse.y: Fix locations of dsym

* parse.y (dsym_node_gen): Always set locations
  to include locations of tSYMBEG and tSTRING_END.

  e.g. The locations of the NODE_LIT is fixed:

  ```
  :"a"
  ```

  * Before

  ```
  NODE_LIT (line: 1, code_range: (1,2)-(1,3))
  ```

  * After

  ```
  NODE_LIT (line: 1, code_range: (1,0)-(1,4))
  ```

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61065 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

parse.y

@@ -10842,11 +10842,13 @@ dsym_node_gen(struct parser_params *parser, NODE *node, const YYLTYPE *location)
     switch (nd_type(node)) {
       case NODE_DSTR:
 	nd_set_type(node, NODE_DSYM);
+	nd_set_loc(node, location);
 	break;
       case NODE_STR:
 	lit = node->nd_lit;
 	add_mark_object(node->nd_lit = ID2SYM(rb_intern_str(lit)));
 	nd_set_type(node, NODE_LIT);
+	nd_set_loc(node, location);
 	break;
       default:
 	node = NEW_NODE(NODE_DSYM, Qnil, 1, new_list(node, location));