Have you looked at the implementations of classes in jQuery, Prototype, Mootools, Dojo, etc? I have. I've used thousands of lines of codes from these libraries and fixed numerous bugs in them.
( Note I'm referring to the 'bind' function specifically in the case of jQuery as it doesn't even provide an equivalent to Class.create(). That said, John Resig himself wrote an article about this and ported out the core of Prototype [ same as I have done ]
http://ejohn.org/blog/simple-javascript-inheritance/ )
Using the prototype may be the way that things get copied from the base definition to an instance, but generally closures are what allow things to have the proper scope. Arguably the scope is far more important for using something like a class than the copying. Additionally, without closures there is no way to pass of anonymous function pointers calling back into the class.
If you think you are demonstrating that I have a lack of knowledge of how this shit works, you are mistaken. But by all means, continue disregarding my points and nitpicking details instead.
You will note that here on hacker news I don't really give a shit about my credibility; I care about providing the most accurate information I can to the benefit of others.
You haven't invalidated my statement about translators at all. ES5, ES6, etc are not cross-browser compatible. Using a translator to "make it work" doesn't count. If you wish to say that C++ is cross browser compatible too then fine, but it is obscuring the root issue that those features do not exist in all the browsers, nor even the whole set of them in any one browser. This is misinformation and will mislead developers.
My last paragraph is in reference to the fact that JS/Ecmascript have never truly been "fixed". It is just a constant hodgepodge of whatever vendors decides to add on to the language.