Undeprecate plural positional argument

```ruby
pluralize people.count, 'person', 'people'
```
reads more naturally than
```ruby
pluralize people.count, 'person', plural: 'people'
```
so let's not deprecate it.

We could label both, but that's a mouthful:
```ruby
pluralize people.count, singular: 'person', plural: 'people'
```

(The `plural:` kwarg shipped in 5.0.0, so we're keeping it.)

1 files changed, 1 insertions, 8 deletions

diff --git a/actionview/lib/action_view/helpers/text_helper.rb b/actionview/lib/action_view/helpers/text_helper.rb
index 0fea4df09c..bd3371ccc8 100644
--- a/actionview/lib/action_view/helpers/text_helper.rb
+++ b/actionview/lib/action_view/helpers/text_helper.rb
@@ -225,14 +225,7 @@ module ActionView
       #
       #   pluralize(2, 'Person', locale: :de)
       #   # => 2 Personen
-      def pluralize(count, singular, deprecated_plural = nil, plural: nil, locale: I18n.locale)
-        if deprecated_plural
-          ActiveSupport::Deprecation.warn("Passing plural as a positional argument " \
-            "is deprecated and will be removed in Rails 5.1. Use e.g. " \
-            "pluralize(1, 'person', plural: 'people') instead.")
-          plural ||= deprecated_plural
-        end
-
+      def pluralize(count, singular, plural_arg = nil, plural: plural_arg, locale: I18n.locale)
         word = if (count == 1 || count =~ /^1(\.0+)?$/)
           singular
         else