addAllFromMultimap(map) {
    map.getEntries().forEach(function(entry) {
      'use strict';
      this.add(entry[0], entry[1]);
    }, this);
  }
Adds the contents of the given map/multimap to this multimap.
@param {!goog.labs.structs.Multimap<K, V>} map The
    map to add.