Merge pull request #37303 from eregon/follow-frozen-symbol-to_s

Use String#+@ before mutating the result of Symbol#to_s

activesupport/lib/active_support/ordered_options.rb

@@ -39,7 +39,7 @@ def [](key)
     end
 
     def method_missing(name, *args)
-      name_string = name.to_s
+      name_string = +name.to_s
       if name_string.chomp!("=")
         self[name_string] = args.first
       else