Few remember, but Adobe tried to submit a variant of ActionScript 3 as an ECMAScript candidate but the open web folks were dubious and it went nowhere. That's

Few remember, but Adobe tried to submit a variant of ActionScript 3 as an ECMAScript candidate but the open web folks were dubious and it went nowhere. That's not the same thing as open-sourcing the Flash authoring tool, but they still sell the modern variant Animate. They could open source the player, but why bother -- the browser vendors have basically shut the gates. The swf file spec is pretty well documented but the player architecture doesn't map well to 2d canvas performance wise and is nearly a complete impedance mismatch for webgl.