option `auto_html5_validation: false` doesn't work when using model's namespace for form_for.

[chrhsmt]

I'm using auto_html5_validation: false option for form_for tag with model object namespace.
ex:
<%= form_for([:admin, @client], auto_html5_validation: false) do |f| %>
so, it doesn't work.

because
variables named 'record' is Array...
in html5_validators's form_helpers.rb L:22