Formatter: Fix Bug where case children were lost

[marcoroth]

This pull request fixes a bug in the formatter where it would drop the children of case/when and case/in statements.

<% case variable %>
  <h1>Children</h1>
<% else %>
  <h1>else</h1>
<% end %>

was formatted as:

<% case variable %>
<% else %>
  <h1>else</h1>
<% end %>

Now they are being preserved:

<% case variable %>
  <h1>Children</h1>
<% else %>
  <h1>else</h1>
<% end %>