compass 增加 autoprefixer 配置

 require 'compass/import-once/activate'
+
+# autoprefixer自动加浏览器前缀
+# 需要先安装, gem install autoprefixer-rails
+
+# require 'autoprefixer-rails'
+#
+# on_stylesheet_saved do |file|
+#   css = File.read(file)
+#   map = file + '.map'
+#   browsers = ['> 1%', 'ie 8']
+#
+#   if File.exists? map
+#     result = AutoprefixerRails.process(css,
+#       from: file,
+#       to:   file,
+#       browsers: browsers,
+#       map:  { prev: File.read(map), inline: false })
+#     File.open(file, 'w') { |io| io << result.css }
+#     File.open(map,  'w') { |io| io << result.map }
+#   else
+#     File.open(file, 'w') { |io| io << AutoprefixerRails.process(css, browsers) }
+#   end
+# end
+
 # Require any additional compass plugins here.
 
 # Set this to the root of your project when deployed: