title: Urls with two leading slashes and without schema
body: <p>Sometimes I see script src or image src without schema, only two leading slashes //</p>
  
  <p>From <a href="http://www.performable.com/" rel="nofollow">http://www.performable.com/</a> home page</p>
  
  <pre><code>&lt;script src="//d2f7h8c8hc0u7y.cloudfront.net/performable/pax/8uEvsz.js"&gt;&lt;/script&gt;
  </code></pre>
  
  <p><a href="http://www.hellobar.com/" rel="nofollow">http://www.hellobar.com/</a> home page - and their integration code</p>
  
  <pre><code>&lt;script type="text/javascript" src="//www.hellobar.com/hellobar.js"&gt;&lt;/script&gt;
  </code></pre>
  
  <p>I've integrated both on my site and see errors in apache log similar to</p>
  
  <pre><code>www.mysite.com//www.hellobar.com/hellobar.js not found
  </code></pre>
  
  <p>However they're rare - less than 1%.</p>
  
  <p>I think double leading slashes is a replacement for http\https and such links will use current page schema. Can someone confirm that?</p>
  
  <p>Also, which browsers have support for that urls and which have problems?</p>