Remove object spread operator so old edge works

[Lego6245]

Old edge doesn't support the spread operator for object literals. We can make a simple one line change that use Object.assign instead which does basically the same thing, but allows for users still using old edge to use the site.

We should consider a transpile step to fix this class of issues automatically for devs (and potentially show a banner warning for browsers that aren't supported)

Fixes #383

[rctgamer3]

Is this broken in Edge (Webkit)?