Sprockets shouldn't be in debug mode by default in development (rails#42984)

* Sprockets shouldn't be in debug mode by default in development

As we move to separate files with ESM, we won't be concatenating or even preprocessing large JavaScript at all. Debug mode is thus irrelevant.

* Debug mode is no longer default

Author: David Heinemeier Hansson

railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt

@@ -62,11 +62,6 @@ Rails.application.configure do
 
   <%- end -%>
   <%- unless options.skip_sprockets? -%>
-  # Debug mode disables concatenation and preprocessing of assets.
-  # This option may cause significant delays in view rendering with a large
-  # number of complex assets.
-  config.assets.debug = true
-
   # Suppress logger output for asset requests.
   config.assets.quiet = true
   <%- end -%>

railties/test/application/assets_test.rb

@@ -472,9 +472,9 @@ class ::PostsController < ActionController::Base ; end
       class ::PostsController < ActionController::Base; end
 
       get "/posts", {}, { "HTTPS" => "off" }
-      assert_match('src="http://example.com/assets/application.debug.js', last_response.body)
+      assert_match('src="http://example.com/assets/application.js', last_response.body)
       get "/posts", {}, { "HTTPS" => "on" }
-      assert_match('src="https://example.com/assets/application.debug.js', last_response.body)
+      assert_match('src="https://example.com/assets/application.js', last_response.body)
     end
 
     test "asset URLs should be protocol-relative if no request is in scope" do