[Live Range Selection] editing/pasteboard/smart-drag-drop.html fails

https://bugs.webkit.org/show_bug.cgi?id=248799

Reviewed by Wenson Hsieh.

Explicitly set the selection at the beginning of the dragged content.

* LayoutTests/editing/pasteboard/smart-drag-drop.html:

Canonical link: https://commits.webkit.org/257425@main

Author: rniwa

LayoutTests/editing/pasteboard/smart-drag-drop.html

@@ -4,7 +4,9 @@
 <script src="../../resources/dump-as-markup.js"></script>
 <script>
 function editingTest() {
-  
+    test.focus();
+    getSelection().setPosition(dragme.firstChild, 0);
+
     if (!window.eventSender)
         return;
     doubleClickAtSelectionStart();