Implement the Symbol builtin object (#2601)

This patch contains the base functionalities that the new builtin object requires.

Currently unavailable:
 - print (Symbol('foo')) - this features requires the refactor of the print handler function
 - Several global symbol based builtin routines (follow up patch)

JerryScript-DCO-1.0-Signed-off-by: Robert Fancsik frobert@inf.u-szeged.hu

jerry-core/ecma/builtin-objects/ecma-builtin-helpers.c

@@ -187,7 +187,7 @@ ecma_builtin_helper_get_to_locale_string_at_index (ecma_object_t *obj_p, /**< th
  */
 ecma_value_t
 ecma_builtin_helper_object_get_properties (ecma_object_t *obj_p, /**< object */
-                                           bool only_enumerable_properties) /**< list enumerable properties? */
+                                           uint32_t opts) /**< any combination of ecma_list_properties_options_t */
 {
   JERRY_ASSERT (obj_p != NULL);
 
@@ -197,9 +197,7 @@ ecma_builtin_helper_object_get_properties (ecma_object_t *obj_p, /**< object */
 
   uint32_t index = 0;
 
-  ecma_collection_header_t *props_p;
-  props_p = ecma_op_object_get_property_names (obj_p,
-                                               only_enumerable_properties ? ECMA_LIST_ENUMERABLE : ECMA_LIST_NO_OPTS);
+  ecma_collection_header_t *props_p = ecma_op_object_get_property_names (obj_p, opts);
 
   ecma_value_t *ecma_value_p = ecma_collection_iterator_init (props_p);