:classes option doesn't work if followed by a do block

[yulolimum]

@jamonholmgren - I dont think this actually works: https://github.com/infinitered/thesis-phoenix#custom-classes-or-id

<%= content(@conn, "test", :html, classes: "test-class") do %>
  <p>
          Quem firmissimum ullamco quae esse e commodo de incurreret o
          deserunt. Nam e domesticarum, incurreret dolor est officia cohaerescant, de aut
          instituendarum se probant aliqua eram occaecat duis ea nostrud consectetur non
          mentitum, vidisse magna laboris constias, elit officia aut adipisicing ab de
          quorum aute malis officia.
  </p>
<% end %>

However, this works:

<%
  placeholder = """
    <p>At vero eos et accusamus et iusto odio dignissimos
    ducimus qui blanditiis praesentium voluptatum deleniti
    atque corrupti quos dolores.</p>
  """
%>

<%= content(@conn, "test", :html, do: placeholder, classes: "test-class") %>