Avoid blob conversion for specific requests (#752)

Co-authored-by: fdacosta <fabio.costa@disneystreaming.com>
Co-authored-by: Jake Champion <me@jakechampion.name>

fetch.js

@@ -494,8 +494,15 @@ export function fetch(input, init) {
       xhr.withCredentials = false
     }
 
-    if ('responseType' in xhr && support.blob) {
-      xhr.responseType = 'blob'
+    if ('responseType' in xhr) {
+      if (support.blob) {
+        xhr.responseType = 'blob'
+      } else if (
+        support.arrayBuffer &&
+        request.headers.get('Content-Type').indexOf('application/octet-stream') !== -1
+      ) {
+        xhr.responseType = 'arraybuffer'
+      }
     }
 
     request.headers.forEach(function(value, name) {