brew tap homebrew/versions
brew uninstall v8
brew install v8-315
gem uninstall -a libv8
gem install libv8 -v '3.16.14.19' -- --with-system-v8
brew install v8@3.15
bundle config --local build.libv8 --with-system-v8
bundle config --local build.therubyracer --with-v8-dir=/usr/local/opt/v8@3.15
bundle install
https://github.com/cowboyd/libv8/issues/205
https://github.com/cowboyd/libv8/issues/120