These classes / libraries are not built inside a Flash Player. They are part of the SWF file after compilation.
SWF specification is here http://wwwimages.adobe.com/content/dam/Adobe/en/devnet/swf/p... It is definitely shorter and simpler, than e.g. PDF file format.
Re:WebAssembly Browser Preview
by 0xcde4c3db on Tuesday November 01, 2016 @12:12AM
(#12843376)
There's still a pretty big gap between parsing and actually rendering. I don't think that spec contains anywhere near enough information to play animations the same way that Flash Player does.
It's a huge undertaking. There are just a ton of library calls to support. Here's the list of AS3.0 classes: http://help.adobe.com/en_US/FlashPlatform/reference/actionsc...
And a whole lot of games are still in AS2 - game developers never really embraced AS3.
It really isn't going to happen, I'm afraid.
EDIT - Maybe it's possible to compile the C++ sources for the Flash Player to WebAssembly? Then you wouldn't have to re-implement the libraries.
I don't know the state of these compilers, but there was a Mozilla post about it a while back: https://hacks.mozilla.org/2015/12/compiling-to-webassembly-i....
Adobe hasn't open sourced the Flash Player, so it would have to be them.