title: Autoprefixing using Grunt + PostCSS
body: <p>I'm using Sass and rather than create a mixin I'm trying to use grunt-postcss to add my vendor prefixes on my class definitions...</p>
  
  <p>this is my css</p>
  
  <pre><code>@keyframes {
      from { transform:scale(1); }
        to { transform:scale(2); }
  }
  </code></pre>
  
  <p>My gruntfile </p>
  
  <pre><code>watch:{
          sass: {
              files: ["sass/partials/*.scss","sass/*.scss"],
              tasks:['sass','postcss']
          }
      },
      sass :{
          dev: {
              files: {
                  "web/css/styles.css" :  "sass/demo.scss"
              }
          }
      },
      postcss :{
          options: {
              processors:[
                  require('autoprefixer-core')({browsers:'&gt;5%'})
              ]
          },
          dist: {
              src: 'web/css/*.css'
          }
      },
  </code></pre>
  
  <p>But the final file doesn't have the prefixes. What am i doing wrong?</p>
  
  <p>[UPDATE]</p>
  
  <p>i tried changing the </p>
  
  <pre><code>dist: {
     src:
  }
  </code></pre>
  
  <p>to</p>
  
  <pre><code>dist : { files: {}}
  </code></pre>
  
  <p>but still didn't work is this a bug?  i note that no one has tried to use the <strong>@keyframes</strong> definitions before</p>
  
  <p>[UPDATE]</p>
  
  <p>while running the task <strong>postcss:dist</strong> I am getting and error</p>
  
  <blockquote>
    <p>Fatal Error: undefined is not a function </p>
  </blockquote>
  
  <p>Am i missing something here?</p>