Use a sequence for files (#170)

Author: Marcos Cáceres

index.html

@@ -265,7 +265,7 @@ <h3>
         </h3>
         <pre class="idl">
           dictionary ShareData {
-            FrozenArray&lt;File&gt; files;
+            sequence&lt;File&gt; files;
             USVString title;
             USVString text;
             USVString url;