Add IntersectionObserver polyfill

client/js/render.js

@@ -12,6 +12,8 @@ const condensed = require("./condensed");
 const chat = $("#chat");
 const sidebar = $("#sidebar");
 
+require("intersection-observer");
+
 const historyObserver = window.IntersectionObserver ?
 	new window.IntersectionObserver(loadMoreHistory, {
 		root: chat.get(0)

package.json

@@ -73,6 +73,7 @@
     "fuzzy": "0.1.3",
     "handlebars": "4.0.10",
     "handlebars-loader": "1.6.0",
+    "intersection-observer": "0.4.2",
     "jquery": "3.2.1",
     "jquery-textcomplete": "1.8.4",
     "jquery-ui": "1.12.1",