title: Hyphen in attribute value causing AngularJs validation break
body: <p>I just noticed that if i have a hyphen in the form name attribute or the input's name attribute, AngularJS validations don't work.</p>
  
  <p>This doesn't work if i try to validate the fields</p>
  
  <pre><code>&lt;form name="signup-form"&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>The below works perfectly</p>
  
  <pre><code>&lt;form name="signupform"&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>Can someone please explain why AngularJs doesn't work in the first case? And if we were to have "-" work, how can we do that?</p>