Plus a couple of related ActionPack patches.

This makes sure that the labels are linked up with the fields.
Fixes #29014

form_with requires people to pass an id manually, so users can just
prefix their namespace right there.

The test using mathn was first introduced in f1d91790 to check that the
`distance_of_time_in_words` properly doesn't use the `Fixnum#/` method
by explicitly requiring this library as it redefines this method.

Given that `mathn` has been gemified in Ruby 2.5 and is deprecated since
version 2.2, we can certainly safely assume that people will most-likely
not require this library in their application.

However, to make sure that we don't regress, let's add a test similar to
the one before f1d91790.

".. with __dir__ we can restore order in the Universe." - by @fxn

Related to 5b8738c2

This allows auto_discovery_link_tag to support the JSON Feed standard.
See https://jsonfeed.org/version/1 for more information.

see: https://bugs.ruby-lang.org/issues/6696

Allows a custom object implementing Enumerable to be used as the choices
parameter for a select tag, which previously wasn't possible due to the
call to `empty?` on the choices (which isn't implemented on Enumerable).

* Internally all input is converted to time so that it can be treated
  uniformly.

Remove now-unneeded condition

* Now that all input is treated is converted to time, we no longer need
  to type check it.

Rename variables to clarify their purpose

Extract private method to normalize distance_of_time args to time

Update actionview changelog

- `check_parameters` kwargs was added to the `current_page?` method, the implementation was assuming only hashes responds to `delete`. This was causing issues when `current_page?` was called with a Active Model object
- ref https://github.com/rails/rails/pull/27549
- Fixes #28846

- This method was added in this commit https://github.com/rails/rails/commit/33258d713a4bc20b71e92fd656c923a7b189cd33
- The last caller got removed there https://github.com/rails/rails/commit/0b6ce3422370647cad3e91263a291f69b313d65b

Remove unnecessary `skip_default_ids` and `allow_method_names_outside_object` attributes of select tag in `form_with`

This configuration is not present in ActionView::Base so we can't let
the action_view.set_configs initializer set it.

Also add tests to make sure this config works.

Fixes #28824

Closes #28382
Closes #28651

Since this protection is now in Parameters we can use it instead of
reimplementing again.

  -
  Restore ability to accept ecmascript
  JS response should not modify DOM.

The previously referenced file no longer appears to exist in the project.

`'#{name}' file doesn't exist, so no dependencies` was removed in
bb048147.

Action View overrides `url_for` in the view context to render paths by
default when using `url_for` and this means that direct route helpers
don't get the full url when called with the url suffix. To fix this
always call the original `url_for`.

The existing UJS event behavior relies on browsers not sending events for
various events when an element is disabled. For example, imagine the following:

    <button type="submit" disabled="disabled">Click me</button>

The above button is disabled, so browsers will not trigger a click event and
all UJS behavior is prevented. However, imagine a button like this:

    <button type="submit" disabled="disabled"><strong>Click me</strong></button>

The above is treated differently by browsers such as Chrome/Safari. These
browsers do not consider the strong tag to be disabled, and will trigger click
events. UJS has logic to walk up the DOM to find an associated element subject
to UJS behavior. But, this logic does not take into account the disabled
status of the element.

I originally thought we could simply change the selectors used to match
elements to ignore disabled elements. However, UJS disables some elements as
part of the event chain. So, an element might match early in the chain and
then fail to match later. Instead of changing the selectors I added a callback
to the chain that calls `stopEverything` if an element is disabled when the
event chain begins.

Currently `ActiveSupport::Duration` implicitly converts to a seconds
value when used in a calculation except for the explicit examples of
addition and subtraction where the duration is the receiver, e.g:

    >> 2 * 1.day
    => 172800

This results in lots of confusion especially when using durations
with dates because adding/subtracting a value from a date treats
integers as a day and not a second, e.g:

    >> Date.today
    => Wed, 01 Mar 2017
    >> Date.today + 2 * 1.day
    => Mon, 10 Apr 2490

To fix this we're implementing `coerce` so that we can provide a
deprecation warning with the intent of removing the implicit coercion
in Rails 5.2, e.g:

    >> 2 * 1.day
    DEPRECATION WARNING: Implicit coercion of ActiveSupport::Duration
    to a Numeric is deprecated and will raise a TypeError in Rails 5.2.
    => 172800

In Rails 5.2 it will raise `TypeError`, e.g:

    >> 2 * 1.day
    TypeError: ActiveSupport::Duration can't be coerced into Integer

This is the same behavior as with other types in Ruby, e.g:

    >> 2 * "foo"
    TypeError: String can't be coerced into Integer
    >> "foo" * 2
    => "foofoo"

As part of this deprecation add `*` and `/` methods to `AS::Duration`
so that calculations that keep the duration as the receiver work
correctly whether the final receiver is a `Date` or `Time`, e.g:

    >> Date.today
    => Wed, 01 Mar 2017
    >> Date.today + 1.day * 2
    => Fri, 03 Mar 2017

Fixes #27457.

The assertion will ensure that the behavior doesn't regress.
  assert_equal "/projects", polymorphic_path("projects")

Remove FIXME related to polymorphic_url behavior.
polymorphic_url with Symbol or String works equally.
Example:

  default_url_options[:host] = "example.com"

  polymorphic_url(:projects)  # => "http://example.com/projects"
  polymorphic_url("projects") # => "http://example.com/projects"

Related to 37d4415a

```
go get -u github.com/client9/misspell/cmd/misspell
misspell  -w -error -source=text .
```

sub_template_message distracts Rails.root from its message only when Rails.root is defined,
and Rails.root is defined at tools/test.rb

This causes TypeError when loaded separately