title: Intl.NumberFormat currency: $US currency symbol?
body: <p>I don't understand how NumberFormat works.</p>
  
  <p>In France we never use <code>$US</code> so why do I get the following?</p>
  
  <pre><code>new Intl.NumberFormat("fr-FR",{
              style: 'currency',
              currency: 'USD',
              minimumFractionDigits: 2,
           }).format("345")
  "345,00 $US"
  
  new Intl.NumberFormat("fr-FR",{
              style: 'currency',
              currency: 'EUR',
              minimumFractionDigits: 2,
           }).format("345")
  "345,00 €"
  </code></pre>
  
  <p>Also: the following does not make any sense to me either. I tried random locales to see the impact and get different results for these 2:</p>
  
  <pre><code>new Intl.NumberFormat("en-HOS",{
              style: 'currency',
              currency: 'USD',
              minimumFractionDigits: 2,
           }).format("345")
  "345,00 $US"
  
  new Intl.NumberFormat("en-HOSSDDG",{
              style: 'currency',
              currency: 'USD',
              minimumFractionDigits: 2,
           }).format("345")
  "$345.00"
  </code></pre>
  
  <p>Is this API broken or I miss something?</p>