Fix inherit from deprecated `ActionView::Template::Handlers::Erubis`

There are some classes inherit from `ActionView::Template::Handlers::Erubis`.
(ex. https://github.com/haml/haml/blob/4.0.7/lib/haml/helpers/safe_erubis_template.rb#L3)

```
Class.new(ActionView::Template::Handlers::Erubis)
# => TypeError: superclass must be a Class (ActiveSupport::Deprecation::DeprecatedConstantProxy given)
```

2 files changed, 10 insertions, 1 deletions

diff --git a/actionview/lib/action_view/template/handlers/erb.rb b/actionview/lib/action_view/template/handlers/erb.rb
index cee5408aa9..58c7fd1a88 100644
--- a/actionview/lib/action_view/template/handlers/erb.rb
+++ b/actionview/lib/action_view/template/handlers/erb.rb
@@ -1,7 +1,7 @@
 module ActionView
   class Template
     module Handlers
-      Erubis = ActiveSupport::Deprecation::DeprecatedConstantProxy.new("Erubis", "ActionView::Template::Handlers::ERB::Erubis", message: "ActionView::Template::Handlers::Erubis is deprecated and will be removed from Rails 5.2. Switch to ActionView::Template::Handlers::ERB::Erubi instead.")
+      autoload :Erubis, "action_view/template/handlers/erb/deprecated_erubis"
 
       class ERB
         autoload :Erubi, "action_view/template/handlers/erb/erubi"
diff --git a/actionview/lib/action_view/template/handlers/erb/deprecated_erubis.rb b/actionview/lib/action_view/template/handlers/erb/deprecated_erubis.rb
new file mode 100644
index 0000000000..427ea20064
--- /dev/null
+++ b/actionview/lib/action_view/template/handlers/erb/deprecated_erubis.rb
@@ -0,0 +1,9 @@
+::ActiveSupport::Deprecation.warn("ActionView::Template::Handlers::Erubis is deprecated and will be removed from Rails 5.2. Switch to ActionView::Template::Handlers::ERB::Erubi instead.")
+
+module ActionView
+  class Template
+    module Handlers
+      Erubis = ERB::Erubis
+    end
+  end
+end