code: function ReflectiveInjector_(_providers, _parent) {
          if (_parent === void 0) { _parent = null; }
          /** @internal */
          this._constructionCounter = 0;
          this._providers = _providers;
          this._parent = _parent;
          var len = _providers.length;
          this.keyIds = new Array(len);
          this.objs = new Array(len);
          for (var i = 0; i < len; i++) {
              this.keyIds[i] = _providers[i].key.id;
              this.objs[i] = UNDEFINED;
          }
      }
docs: Private
  @param {?} _providers
  @param {?=} _parent