[ruby/irb] Simplify irb_info command

(https://github.com/ruby/irb/pull/597)

https://github.com/ruby/irb/commit/0a0409c52b

lib/irb/cmd/irb_info.rb

@@ -11,8 +11,6 @@ module IRB
       description "Show information about IRB."
 
       def execute
-        Class.new {
-          def inspect
         str  = "Ruby version: #{RUBY_VERSION}\n"
         str += "IRB version: #{IRB.version}\n"
         str += "InputMethod: #{IRB.CurrentContext.io.inspect}\n"
@@ -25,10 +23,8 @@ module IRB
           codepage = `chcp`.b.sub(/.*: (\d+)\n/, '\1')
           str += "Code page: #{codepage}\n"
         end
-            str
-          end
-          alias_method :to_s, :inspect
-        }.new
+        puts str
+        nil
       end
     end
   end