Layout support for Symbol instances
Great work on supporting Symbols! 

I had a quick try and I'm curious what's the plan for integrating the Symbol support with css-layout so that Symbol instances may act like first-class citizens within a rendered layout?

As far as I understand right now, and from my limited testing, css-layout requires explicit widths and heights to be passed to a Symbol instance or it will render as a 0x0 layer.

Have you considered feeding css-layout the actual raw contents of the symbol master at layout time, with overrides applied, so that it will take full advantage of the constraints, and then replacing this at render time with an instance of the corresponding symbol whose width and height and position are set based on the layout?

I have a few hours free so I will have a look at the code and maybe take a stab at this, but I cannot guarantee anything. If anyone else is working on this, give me a heads-up!