restore using_spec.rb

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66022 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

spec/ruby/core/main/using_spec.rb

@@ -6,11 +6,9 @@ describe "main.using" do
     lambda do
       eval('using', TOPLEVEL_BINDING)
     end.should raise_error(ArgumentError)
-=begin
     lambda do
       eval('using "foo"', TOPLEVEL_BINDING)
     end.should raise_error(TypeError)
-=end
   end
 
   it "uses refinements from the given module only in the target file" do