register_engine would take a varargs

Author: amatsuda

lib/sass/rails/railtie.rb

@@ -56,11 +56,11 @@ class Railtie < ::Rails::Railtie
       config.assets.configure do |env|
         if env.respond_to?(:register_engine)
           args = ['.sass', Sass::Rails::SassTemplate]
-          args << { silence_deprecation: true } if env.method(:register_engine).arity > 2
+          args << { silence_deprecation: true } if env.method(:register_engine).arity.abs > 2
           env.register_engine *args
 
           args = ['.scss', Sass::Rails::ScssTemplate]
-          args << { silence_deprecation: true } if env.method(:register_engine).arity > 2
+          args << { silence_deprecation: true } if env.method(:register_engine).arity.abs > 2
           env.register_engine *args
         end