PHP Version 5.5 Formula was removed
Last versions were

Revision: 12

php55 requires the following formulae to be installed:
enchant 2.2.3 Spellchecker wrapping library
freetype 2.9 Software library to render fonts
gettext GNU internationalization (i18n) and localization (l10n) library
gmp 6.1.2_2 GNU multiple precision arithmetic library
icu4c 61.1 C/C++ and Java libraries for Unicode and globalization
jpeg 9c Image manipulation library
libvpx 1.7.0 VP8/VP9 video codec
libpng 1.6.34 Library for manipulating PNG images
libxml2 2.9.7 GNOME XML library
unixodbc 2.3.6 ODBC 3 connectivity for UNIX
readline 7.0.3_1 Library for command-line editing
openssl 1.0.2o_1 SSL/TLS cryptography library

Recent formula history

Mike McQuaid Deprecate tap.
Srihari Thalla php55: Bump revision
Elan Ruusamäe fix PHPDBG_SRC_TARBAL typo
Jan Viljanen php55: readline rev bottle update
Jan Viljanen php55: update bottle

Formula code at GitHub