Suppose you have two resources routed in the following manner:
```ruby
resources :blogs do
resources :posts
end
resources :posts
```
When using polymorphic resource routing like `url_for([@blog, @post])`, and `@blog` is `nil` Rails should still try to match the route to the top-level posts resource.
Fixes#16754
The message passed to Minitest's assert_raise is used as output in case
the assertion fails, but we can test against the exact message by using
the actual exception object that is returned from the assert_raise call.
We are dropping HTML 4.01 and XHTML strict compliance since input
tags directly inside a form are valid HTML5, and the absense of
inline styles help in validating for Content Security Policy.
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
