list of supported builtins or intrinsic and/or core classes

Hello,

is there a listing somewhere that list supported builtins when converting AS3 to JS ?

so I'm not only talking about `Object`, `Boolean`, `Number`, etc.
but also about classes like `Dictionary`, `ByteArray`, `Proxy`, etc.

and related to that what are the "supported features"
or simply which version of JS does it support? ES3? ES5.1? ES6?

for ex: with the AS3 `String` class
can I use the `trim()` method if I know the target will support ES5.1?
see [MDN String.trim()](http://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/Trim)

other ex: what about statements like `as`, `is` ? or using namespace?

It is already great we can use E4X and `Vector`, but I'm just trying to get a 10000 feet view of the language support (if you can call it like that?)

No repository file, test, or documentation entry point is identified in the issue. First locate the existing documentation for AS3-to-JS conversion and determine where supported builtins, classes, language features, and JavaScript versions are described; done means providing a maintained, accurate overview that answers the listed examples.

Written by the indexing model from the issue text.