Convert previous CS6 FLA/AS to CC FLA/JS

Hi,

I have to convert some FLA/AS to FLA/JS with all AS code out of the timeline as packages/classes.

knowing that AS/JS must be done manually (btw is there any EcmaScript version we can keep AS syntax like packages and classes?) my worry is how to open a CS6 FLA with movieclips and as2/3 components and convert it in html5?

thanks