Update the RegExp constructor to ECMA-262 v6 (#3538)

The following methods have been implemented:
- RegExpAlloc, based on ECMA-262 v6, 21.2.3.2.1
- RegExpInitialize, based on ECMA-262 v6, 22.2.3.2.2
- RegExpCreate, based on ECMA-262 v6, 21.2.3.2.3

Co-authored-by: Robert Fancsik frobert@inf.u-szeged.hu
JerryScript-DCO-1.0-Signed-off-by: Adam Szilagyi aszilagy@inf.u-szeged.hu

jerry-core/ecma/base/ecma-helpers.c

@@ -1494,6 +1494,28 @@ ecma_compiled_code_get_tagged_template_collection (const ecma_compiled_code_t *b
 } /* ecma_compiled_code_get_tagged_template_collection */
 #endif /* ENABLED (JERRY_ES2015) */
 
+/**
+ * Helper function to check if the given value is a class
+ *
+ * @return pointer to the extended object - if 'this' is a class
+ *         NULL- otherwise
+ */
+ecma_extended_object_t *
+ecma_op_check_object_type_is_class (ecma_value_t this)  /**< this value */
+{
+  if (ecma_is_value_object (this))
+  {
+    ecma_object_t *obj_p = ecma_get_object_from_value (this);
+
+    if (ecma_get_object_type (obj_p) == ECMA_OBJECT_TYPE_CLASS)
+    {
+      return (ecma_extended_object_t *) obj_p;
+    }
+  }
+
+  return NULL;
+} /* ecma_op_check_object_type_is_class */
+
 #if ENABLED (JERRY_LINE_INFO) || ENABLED (JERRY_ES2015_MODULE_SYSTEM) || ENABLED (JERRY_ES2015)
 /**
  * Get the number of formal parameters of the compiled code