Gemfile in uglifier-2.5.0 vs Gemfile in uglifier-2.5.1

@@ -1,7 +1,16 @@
 source "https://rubygems.org"
 
 gemspec
 
 platforms :rbx do
+  gem 'racc'
   gem 'rubysl', '~> 2.0'
+  gem 'psych'
 end
+
+if RUBY_VERSION >= '1.9'
+  gem 'rubocop', '~> 0.23.0', :group => [:development]
+else
+  gem 'execjs', '~> 2.0.2'
+end
+