Clean up Mime::Type and remove deprecated stuff (from 2.3).

actionpack/lib/action_dispatch/http/mime_type.rb

@@ -52,12 +52,6 @@ class Type
     cattr_reader :browser_generated_types
     attr_reader :symbol
 
-    @@unverifiable_types = Set.new [:text, :json, :csv, :xml, :rss, :atom, :yaml]
-    def self.unverifiable_types
-      ActiveSupport::Deprecation.warn("unverifiable_types is deprecated and has no effect", caller)
-      @@unverifiable_types
-    end
-
     # A simple helper class used in parsing the accept header
     class AcceptItem #:nodoc:
       attr_accessor :order, :name, :q
@@ -100,7 +94,7 @@ def register_alias(string, symbol, extension_synonyms = [])
       end
 
       def register(string, symbol, mime_type_synonyms = [], extension_synonyms = [], skip_lookup = false)
-        Mime.instance_eval { const_set symbol.to_s.upcase, Type.new(string, symbol, mime_type_synonyms) }
+        Mime.const_set(symbol.to_s.upcase, Type.new(string, symbol, mime_type_synonyms))
 
         SET << Mime.const_get(symbol.to_s.upcase)