avoid block_given? in enum.rb to reduce method calls
Use suitable type.
Avoid block_given? in mrbgem:enum.rb to reduce method calls
Merge pull request #2686 from cubicdaiya/use-suitable-type

Use suitable type.
Merge pull request #2687 from suzukaze/avoid_block_given

Avoid block_given? in mrbgem:enum.rb to reduce method calls