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--