Merge pull request #20406 from yoongkang/add_edge_sprockets

Use sprockets-rails from github repo

railties/lib/rails/generators/app_base.rb

@@ -208,11 +208,13 @@ def rails_gemfile_entry
         if options.dev?
           [
             GemfileEntry.path('rails', Rails::Generators::RAILS_DEV_PATH),
+            GemfileEntry.github('sprockets-rails', 'rails/sprockets-rails'),
             GemfileEntry.github('arel', 'rails/arel')
           ]
         elsif options.edge?
           [
             GemfileEntry.github('rails', 'rails/rails'),
+            GemfileEntry.github('sprockets-rails', 'rails/sprockets-rails'),
             GemfileEntry.github('arel', 'rails/arel')
           ]
         else