js: Purge useless IIFEs.

With webpack, variables declared in each file are already file-local
(Global variables need to be explicitly exported), so these IIFEs are
no longer needed.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

static/js/upload.js

@@ -1,7 +1,3 @@
-var upload = (function () {
-
-var exports = {};
-
 function make_upload_absolute(uri) {
     if (uri.indexOf(compose.uploads_path) === 0) {
         // Rewrite the URI to a usable link
@@ -199,10 +195,4 @@ exports.options = function (config) {
     };
 };
 
-return exports;
-}());
-
-if (typeof module !== 'undefined') {
-    module.exports = upload;
-}
-window.upload = upload;
+window.upload = exports;