fixes https://github.com/readium/readium-shared-js/issues/384 incorrect pageIndex when navigating links
fixes https://github.com/readium/readium-shared-js/issues/384 incorrect pageIndex when navigating links

JoMedia/readium-shared-js,NYPL-Simplified/readium-shared-js,NYPL/readium-shared-js,NYPL-Simplified/readium-shared-js,NYPL/readium-shared-js,readium/readium-shared-js,readium/readium-shared-js