Added a mechanism for making getImageSync work on HTML.
Added a mechanism for making getImageSync work on HTML.

It's somewhat hacky in that it just preconfigures the width and height based on
a preloaded image manifest (which the app can provide however it wants). But
it's simple and it does what is needed for most apps that just want to be able
to immediately make size decisions after loading an image. The rest of the
rendering pipeline takes care not to freak out about not-yet-loaded images.

tinkerstudent/playn,rachelharvey/playn,playn/playn,rachelharvey/playn,tinkerstudent/playn,ruslansennov/playn2,thecocce/playn-1,playn/playn,ruslansennov/playn2,longtaoge/playn,playn/playn,longtaoge/playn,thecocce/playn-1