Scroll collapsed file into view (#23702)

web_src/js/features/file-fold.js

@@ -8,6 +8,9 @@ import {svg} from '../svg.js';
 export function setFileFolding(fileContentBox, foldArrow, newFold) {
   foldArrow.innerHTML = svg(`octicon-chevron-${newFold ? 'right' : 'down'}`, 18);
   fileContentBox.setAttribute('data-folded', newFold);
+  if (newFold && fileContentBox.getBoundingClientRect().top < 0) {
+    fileContentBox.scrollIntoView();
+  }
 }
 
 // Like `setFileFolding`, except that it automatically inverts the current file folding state.