use proper typographical × instead of x

app/assets/javascripts/discourse/lib/lightbox.js.es6

@@ -48,7 +48,6 @@ export default function($elem) {
               escapeExpression(item.el.attr("title")),
               $("span.informations", item.el)
                 .text()
-                .replace("x", "×")
             ];
             if (
               !Discourse.SiteSettings.prevent_anons_from_downloading_files ||

lib/cooked_post_processor.rb

@@ -421,7 +421,7 @@ class CookedPostProcessor
     img.add_next_sibling(meta)
 
     filename = get_filename(upload, img["src"])
-    informations = "#{original_width}x#{original_height}"
+    informations = "#{original_width}×#{original_height}"
     informations << " #{number_to_human_size(upload.filesize)}" if upload
 
     a["title"] = CGI.escapeHTML(img["title"] || filename)