Revert "Don't remove trailing slash from PATH_INFO for mounted apps"

The revert is needed because of a regression described in #13369, routes
with trailing slash are no longer recognized properly.

This reverts commit 50311f1.

actionpack/CHANGELOG.md

@@ -431,10 +431,4 @@
 
     *Piotr Sarnacki*, *Łukasz Strzałkowski*
 
-*   Fix removing trailing slash for mounted apps.
-
-    Fixes #3215.
-
-    *Piotr Sarnacki*
-
 Please check [4-0-stable](https://github.com/rails/rails/blob/4-0-stable/actionpack/CHANGELOG.md) for previous changes.

actionpack/lib/action_dispatch/journey/router.rb

@@ -54,7 +54,7 @@ def initialize(routes, options)
       end
 
       def call(env)
-        env['PATH_INFO'] = normalize_path(env['PATH_INFO'])
+        env['PATH_INFO'] = Utils.normalize_path(env['PATH_INFO'])
 
         find_routes(env).each do |match, parameters, route|
           script_name, path_info, set_params = env.values_at('SCRIPT_NAME',
@@ -103,12 +103,6 @@ def visualizer
 
       private
 
-        def normalize_path(path)
-          path = "/#{path}"
-          path.squeeze!('/')
-          path
-        end
-
         def partitioned_routes
           routes.partitioned_routes
         end

actionpack/test/dispatch/mount_test.rb

@@ -44,11 +44,6 @@ def test_app_name_is_properly_generated_when_engine_is_mounted_in_resources
           "A named route should be defined with a parent's prefix"
   end
 
-  def test_trailing_slash_is_not_removed_from_path_info
-    get "/sprockets/omg/"
-    assert_equal "/sprockets -- /omg/", response.body
-  end
-
   def test_mounting_sets_script_name
     get "/sprockets/omg"
     assert_equal "/sprockets -- /omg", response.body