Better printing of sparse arrays in console.log
Better printing of sparse arrays in console.log

- Until now, an array constructed with Array(12) was printed as `[]`
  because fh_debug_arr incorrectly made assumptions based on the
  hashmap, without taking sparse arrays into account.

  An array constructed with Array(12) now is printed like this:
  [ , , , , , , , , , , ,  ]
  which matches the behavior in Node.js

ndreynolds/flathead,ndreynolds/flathead