Rollup merge of #98092 - GuillaumeGomez:fix-sidebar-items-expand-collapse, r=notriddle

Fix sidebar items expand collapse

The collapse/expand event was not working for the items in the source code viewer sidebar (talking about these items:

![Screenshot from 2022-06-14 11-21-58](https://user-images.githubusercontent.com/3050060/173543346-af056928-e921-458f-b918-60f6fd0ecbde.png)

).

This PR fixes it and adds a GUI test to prevent another regression.

r? ```@notriddle```

1 files changed, 3 insertions, 3 deletions

diff --git a/src/librustdoc/html/static/js/source-script.js b/src/librustdoc/html/static/js/source-script.js
index 58c036e0b3c..14d8a942977 100644
--- a/src/librustdoc/html/static/js/source-script.js
+++ b/src/librustdoc/html/static/js/source-script.js
@@ -32,10 +32,10 @@ function createDirEntry(elem, parent, fullPath, currentFile, hasFoundFile) {
     fullPath += elem["name"] + "/";
 
     name.onclick = () => {
-        if (hasClass(this, "expand")) {
-            removeClass(this, "expand");
+        if (hasClass(name, "expand")) {
+            removeClass(name, "expand");
         } else {
-            addClass(this, "expand");
+            addClass(name, "expand");
         }
     };
     name.innerText = elem["name"];