[cm6] fix toolbar overflow button calculation (#13669)

GitOrigin-RevId: 11380a5661067a285e0c0de82a37e085fc395f03

services/web/frontend/js/features/source-editor/components/codemirror-toolbar.tsx

@@ -53,7 +53,7 @@ const Toolbar = memo(function Toolbar() {
   const buildOverflow = useCallback(
     (element: Element) => {
       setOverflowOpen(false)
-      setOverflowed(false)
+      setOverflowed(true)
 
       if (overflowBeforeRef.current) {
         overflowedItemsRef.current = new Set()