FIX: browser infinite recursion when editing post

This was a result of:

c4ed353fae

jQuery map on a jQuery object, returns a jQuery object http://api.jquery.com/map/

So you need to convert it to an array prior to mapping

app/assets/javascripts/pretty-text/image-short-url.js.es6

@@ -33,7 +33,7 @@ function _loadCachedShortUrls($images) {
 }
 
 function _loadShortUrls($images, ajax) {
-  const urls = $images.map(img => $(img).data("orig-src"));
+  const urls = $images.toArray().map(img => $(img).data("orig-src"));
   lookupUncachedUploadUrls(urls, ajax).then(() =>
     _loadCachedShortUrls($images)
   );