LinkedHashMap< K, V>.from constructor
    Creates a LinkedHashMap that contains all key value pairs of other.
The keys must all be instances of K and the values to V.
The other map itself can have any type.
Implementation
factory LinkedHashMap.from(Map other) {
  LinkedHashMap<K, V> result = new LinkedHashMap<K, V>();
  other.forEach((k, v) {
    result[k] = v;
  });
  return result;
}