Don't create unnecessary arrays
Don't create unnecessary arrays

If you pass in `nil`, a string, or another node, it would wrap it in an
array. This would normally be fine, but this is an intense hotspot in
virtual DOM generation (the slowest part of Clearwater's rendering), so
we don't want to create objects unnecessarily.

clearwater-rb/clearwater,elia/clearwater,clearwater-rb/clearwater,elia/clearwater