I quickly tried installing only these two gems and got the following dependency tree in my Gemfile.lock.
sass-rails (3.2.6)
railties (~> 3.2.0)
sass (>= 3.1.10)
tilt (~> 1.3)
slim (2.0.2)
temple (~> 0.6.6)
tilt (>= 1.3.3, < 2.1)
, , slim-2.0.2, 1.3.3 , , sass-rails