Fix extra scrollbar when a popover extends past the viewport. (#62894)

Co-authored-by: tellthemachines <isabel_brison@git.wordpress.org>
Co-authored-by: talldan <talldanwp@git.wordpress.org>

packages/editor/src/components/visual-editor/style.scss

@@ -19,7 +19,7 @@
 
 	// In the iframed canvas this keeps extra scrollbars from appearing (when block toolbars overflow). In the
 	// legacy (non-iframed) canvas, overflow must not be hidden in order to maintain support for sticky positioning.
-	.is-iframed {
+	&.is-iframed {
 		overflow: hidden;
 	}