Merge pull request #3420 from udzura/patch-1

Fix usage of Class#name in mruby-bin-mruby's bintest

mrbgems/mruby-bin-mruby/bintest/mruby.rb

@@ -52,7 +52,7 @@ assert('garbage collecting built-in classes') do
 NilClass = nil
 GC.start
 Array.dup
-print nil.class.name
+print nil.class.to_s
 RUBY
   script.flush
   assert_equal "NilClass", `#{cmd('mruby')} #{script.path}`