mapsEqual function

bool mapsEqual (Map a, Map b)

Checks Maps a and b for equality.

Returns true if a and b are both null, or they are the same length and every key k in a exists in b and the values a[k] == b[k].

Implementation 

bool mapsEqual(Map a, Map b) {
  if (a == b) return true;
  if (a == null || b == null) return false;
  if (a.length != b.length) return false;

  for (var k in a.keys) {
    var bValue = b[k];
    if (bValue == null && !b.containsKey(k)) return false;
    if (bValue != a[k]) return false;
  }

  return true;
}