[a, ..., b] = c doesn't declare ref

[edemaine]

[a, ..., b] = c transpiles to [a, ...ref] = c, [b] = ref.splice(-1), with no declaration of ref.

The path being followed here:

• BindingElement
• BindingRestElement
• EmptyBindingPattern creates a ref, but no process function declares these refs. (It works in the context of pattern matching.)