polyfill.gemspec in polyfill-0.3.0 vs polyfill.gemspec in polyfill-0.4.0

- old
+ new

@@ -23,6 +23,7 @@
   spec.require_paths = ['lib']
 
   spec.add_development_dependency 'bundler', '~> 1.14'
   spec.add_development_dependency 'rake', '~> 10.0'
   spec.add_development_dependency 'rspec', '~> 3.5'
+  spec.add_development_dependency 'rubocop', '~> 0.47.1'
 end