Change effective on 09 February 2016
The following runtimes are now available for PHP applications on Heroku:
The following extensions have been updated:
ext-apcuversion 5.1.3 (for PHP 7.0)
ext-blackfireversion 1.9.0 (for all PHP versions)
ext-phalconversion 2.0.10 (for PHP 5.5 and 5.6)
ext-blackfire extension is now available for PHP 7.