Remove useless pointer keeping

lib/datastore.js

@@ -91,7 +91,6 @@ Datastore.prototype.ensureIndex = function (options, cb) {
   if (!options.fieldName) { return callback({ missingFieldName: true }); }
   if (this.indexes[options.fieldName]) { return callback(); }
 
-  options.datastore = this;
   this.indexes[options.fieldName] = new Index(options);
 
   try {

lib/indexes.js

@@ -15,13 +15,11 @@ function checkValueEquality (a, b) {
 /**
  * Create a new index
  * @param {String} options.fieldName On which field should the index apply (can use dot notation to index on sub fields)
- * @param {Datastore} options.datastore Datastore on which the index is created
  * @param {Boolean} options.unique Optional, enforce a unique constraint (default: false)
  * @param {Boolean} options.sparse Optional, allow a sparse index (we can have documents for which fieldName is undefined) (default: false)
  */
 function Index (options) {
   this.fieldName = options.fieldName;
-  this.datastore = options.datastore;
   this.unique = options.unique || false;
   this.sparse = options.sparse || false;