More backwards compatible changes to sync with ember-cli-test (PR #11718)

[eviltrout]

The big changes here are to initializers to support running tests in Ember CLI as well as the legacy (current) branch.

GitHub

[CvX]

app/assets/javascripts/discourse/app/pre-initializers/discourse-bootstrap.js

@@ -26,23 +27,38 @@ export default {
     if (isTesting()) {
       return;
     }
-    const preloadedDataElement = document.getElementById("data-preloaded");
-    const setupData = document.getElementById("data-discourse-setup").dataset;
 
-    if (preloadedDataElement) {
-      const preloaded = JSON.parse(preloadedDataElement.dataset.preloaded);
+    let setupData;
+    let preloaded;
+    if (app.bootstrap) {
+      // This is annoying but our old way of using `data-*` attributes used camelCase by default
+      setupData = {};
+      Object.keys(app.bootstrap.setup_data).forEach((k) => {
+        setupData[camelize(k)] = app.bootstrap.setup_data[k];
+      });
+      preloaded = app.bootstrap.preloaded;
+    }
 
-      Object.keys(preloaded).forEach(function (key) {
-        PreloadStore.store(key, JSON.parse(preloaded[key]));
+    const setupDataElement = document.getElementById("data-discourse-setup");
+    if (setupDataElement) {
+      setupData = document.getElementById("data-discourse-setup").dataset;

      setupData = setupDataElement.dataset;