dependency on prototype-rails seems to conflict with 5.0+ upgrades

[gessel]

The Gemfile calls gem 'prototype-rails', git: 'https://github.com/rails/prototype-rails.git', branch: '4.2'

which, alas:

In any case, this gem will NOT be officially supported on Rails 5.0 and above.

Might this dependency be circumvented? SJR?