title: Grunt watch with template syntax
body: <p>I'm trying to configure Grunt to watch my less files, but it's getting into some sort of recursive error loop.</p>
  
  <p>Here's the relevant parts of <code>Gruntfile.js</code>:</p>
  
  <pre><code>watch: {
      ...
      less: {
          files: ['&lt;%= less.dev.files %&gt;'],
          tasks: ['less:dev']
      }
  },
  
  less: {
      options: {
          paths: 'www/css',
          strictMath: true,
          strictUnits: true
      },
      dev: {
          options: {
              cleancss: false
          },
          files: {
              'www/css/main.css' : 'www/css/main.less'
          }
      },
      ...
  }
  </code></pre>
  
  <p>As soon as I runt <code>grunt watch:less</code> in my terminal, I get this:</p>
  
  <blockquote>
    <p>Running "watch:less" (watch) task
    Waiting...Warning: Object # has no method 'indexOf'</p>
    
    <p>Running "watch:less" (watch) task
    Waiting...Warning: An error occurred while processing a template (Maximum call stack size exceeded).<br>
    Warning: An error occurred while processing a template (An error occurred while processing a template (Maximum call stack size exceeded).).
    Warning: Object # has no method 'indexOf'</p>
  </blockquote>
  
  <p>Which repeats for quite awhile until it bails out.</p>
  
  <p>It appears <code>&lt;%= less.dev.files %&gt;</code> is confusing it. Why? Is that not the right syntax?</p>