Unexpected "fromEntries" result with `null`

[Eswcvlad]

In the implementation we have this:

• fromEntries(`null`) -> TypeError
• fromEntries(`[]`) -> {}

Based on the spec, these cases should be equivalent and return {}.

[JohnBrinkman]

The implementation won't coerce a null to an array-of-arrays, ~but will coerce an empty array to an array-of-arrays.~ ~I'll change the implementation to explicitly allow an empty array.~ Actually, the implementation was not coercing an empty array, but was failing to coerce null to an array of arrays.