rustdoc: use CSS `overscroll-behavior` instead of JavaScript

Fixes the desktop scrolling weirdness mentioned in
https://github.com/rust-lang/rust/pull/98775#issuecomment-1182575603

As described in the MDN page for this property:

* The current Firefox ESR is 102, and the first Firefox version
  to support this feature is 59.
* The current Chrome version 112, and the first version to support
  this is 63.
* Edge is described as having a minor bug in `none` mode, but we
  use `contain` mode anyway, so it doesn't matter.
* Safari 16, released September 2022, is the last browser to
  add this feature, and is also the oldest version we officially
  support.

1 files changed, 6 insertions, 3 deletions

diff --git a/src/librustdoc/html/static/js/source-script.js b/src/librustdoc/html/static/js/source-script.js
index 6c0f03b5bb0..9aa75517330 100644
--- a/src/librustdoc/html/static/js/source-script.js
+++ b/src/librustdoc/html/static/js/source-script.js
@@ -15,8 +15,13 @@ const NAME_OFFSET = 0;
 const DIRS_OFFSET = 1;
 const FILES_OFFSET = 2;
 
+// WARNING: RUSTDOC_MOBILE_BREAKPOINT MEDIA QUERY
+// If you update this line, then you also need to update the media query with the same
+// warning in rustdoc.css
+const RUSTDOC_MOBILE_BREAKPOINT = 700;
+
 function closeSidebarIfMobile() {
-    if (window.innerWidth < window.RUSTDOC_MOBILE_BREAKPOINT) {
+    if (window.innerWidth < RUSTDOC_MOBILE_BREAKPOINT) {
         updateLocalStorage("source-sidebar-show", "false");
     }
 }
@@ -69,12 +74,10 @@ function createDirEntry(elem, parent, fullPath, hasFoundFile) {
 function toggleSidebar() {
     const child = this.parentNode.children[0];
     if (child.innerText === ">") {
-        window.rustdocMobileScrollLock();
         addClass(document.documentElement, "source-sidebar-expanded");
         child.innerText = "<";
         updateLocalStorage("source-sidebar-show", "true");
     } else {
-        window.rustdocMobileScrollUnlock();
         removeClass(document.documentElement, "source-sidebar-expanded");
         child.innerText = ">";
         updateLocalStorage("source-sidebar-show", "false");