postcss-loader配置好了，运行之后也没有报错，可是在浏览器中查看并没有加上前缀，问什么？

postcss-loader配置好了，运行之后也没有报错，可是在浏览器中查看并没有加上前缀，好疑惑？？麻烦老师、大神帮忙看下，谢谢！！

以下是代码：

var htmlWebpackPlugin=require("html-webpack-plugin");

var path=require('path');

var webpack = require('webpack');

module.exports={

     entry:"./src/app.js",

     output:{

         path:"/webpack_demo/dist",

         filename:"js/[name].js",

     },

     module:{

         rules:[

             {

                 test:/\.js$/,

                 loader:'babel-loader',

                 exclude:path.resolve(__dirname,'node_modules'),

                 include:path.resolve(__dirname,'src/'),

                 query:{

                 presets:['latest']

             }

             },

             {

                 test:/.\css$/,

                 loader:'style-loader!css-loader?importLoaders=1!postcss-loader'

             }

         ]

     },

     plugins:[

             new htmlWebpackPlugin({

                     template:"index.html",

                     filename:"index.html",

                     inject:"body"

             }),

             new webpack.LoaderOptionsPlugin({

                      options: {

                                postcss: function() {

                                          return [

                                            require('autoprefixer')({

                                              broswers: ['last 5 versions']

                                            })

                                          ]

                                }

                      }

                })

     ]

}