title: ES2015 import doesn't work (even at top-level) in Firefox
body: <p>These are my sample files:</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
    &lt;title&gt;Test&lt;/title&gt;
    &lt;script src="t1.js"&gt;&lt;/script&gt;
  &lt;/head&gt;
  &lt;body&gt;&lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>t1.js:</p>
  
  <pre><code>import Test from 't2.js';
  </code></pre>
  
  <p>t2.js:</p>
  
  <pre><code>export const Test = console.log("Hello world");
  </code></pre>
  
  <p>When I load the page in Firefox 46, it returns "SyntaxError: import declarations may only appear at top level of a module" - but I'm not sure how much more top-level the import statement can get here. Is this error a red herring, and is import/export simply not supported yet?</p>