title: JSInterface from webview undefined when backing to previous activity
body: <p>I got a webview, which has a JSInterface :</p>
  
  <pre><code>mWebView.addJavascriptInterface(new JSInterfacelistArticle(mWebView, this, website), "interfaceWebsite");
  </code></pre>
  
  <p>When I use javascript function to call functions from my interface :</p>
  
  <pre><code>window.interfaceWebsite.doToast(info);
  </code></pre>
  
  <p>It's working fine the first time, but when my activity finish(), and then I come back to this one, I got this error :</p>
  
  <pre><code>E/Web Console(28654): Uncaught TypeError: Cannot call method 'doToast' of undefined at :1
  </code></pre>
  
  <p>Why my interface is not working when I start my activity a second time ?</p>
  
  <p>Edit: 
  If I remove window. when I call a function, I got :</p>
  
  <pre><code>Uncaught ReferenceError: interfaceWebsite is not defined at :1
  </code></pre>
  
  <p>So I'm sure my interface has a problem when loading for a second time...</p>
  
  <p>Thanks</p>