[Script API] Unexpected change to properties of native classes

Unexpected change to design of prototype properties including stable APIs as well.

Properties are no longer configurable, this change doesn't applies to methods, only to getters/setters prototype properties.

Steps to reproduce:

 - Try using defineProperty/defineProperties to redefine native properties
 - Unexpected result, in version 1.20.30.20 will throw error, property is not configurable

Expected behavior

This change doesn't follows ECMAScript 6 standards for classes and their prototype fields,

• enumerable: false
• configurable: true

This change shouldn't apply to stable version of modules

Pack to reproduce is available

• compare results on versions 1.20.30.20+, and MC release 1.20.20--