For some reason, if the hash is empty, we choose "optimized" routes. I
am not sure how or why optimized routes differ from regular routes.
But, if we make sure the hash is empty, we get a nice speed improvement.
The use of `display:inline` with the content_tag call in the
extra_tags_for_form method potentially causes display issues with some
browsers, namely Internet Explorer. IE's behaviour of not collapsing
the line height on divs with ostensibly no content means that the
automatically added div containing the hidden authenticity_token, utf8
and _method form input tags may interfere with other visible form
elements in certain circumstances. The use of `display:none` rather
than `display:inline` fixes this problem.
Fixes#6403
:as option should not overwrite :namespace option when
generating html id attribute of the form element. id should be prefixed
by specified namespace even if :as option is present
Add test case showing the issue and code fixing it
