No Object.assign

[andyinabox]

The current version doesn't have a polyfill for Object.assign, looks like it's using an older version of https://github.com/fabianmoronzirfas/extendscript.prototypes ?

Maybe this will be addressed in #24?

[ff6347]

I think the best effort would be to move to the https://github.com/ExtendScript/extendscript-es5-shim I'll put it on the list of todos.