rails/rails — pull request #7888 by xdite (2012-10-09 19:53:23+00:00)
Title: javascripts tags should be placed at the bottom by default

according Best Practices for Speeding Up Your Web Site

http://developer.yahoo.com/performance/rules.html
javascripts should be placed at the bottom

and recommend write javascripts this way

=====
Your view content here
<%= content_for(:scripts) do %>

<% end %>
======