There are various drawing surfaces on the web that don't involve interacting with the DOM (canvas, webgl, etc). I'm not sure what you mean about the IDE? Webas

There are various drawing surfaces on the web that don't involve interacting with the DOM (canvas, webgl, etc). I'm not sure what you mean about the IDE? Webassembly won't restrict what source language you use so you'll be able to use any IDE that supports your chosen language. And that would include Flash and its tools if someone writes a compiler.