Avoid using instanceRoot in layout tests

LayoutTests/svg/custom/use-listener-append-crash.html

Index: LayoutTests/svg/custom/use-listener-append-crash.html
diff --git a/LayoutTests/svg/custom/use-listener-append-crash.html b/LayoutTests/svg/custom/use-listener-append-crash.html
index 5b8b9a1a95c68f4076796bcaa54695c91bfcebce..bf064c8eb9669f5dc435c683fc951bd55fc4342f 100644
--- a/LayoutTests/svg/custom/use-listener-append-crash.html
+++ b/LayoutTests/svg/custom/use-listener-append-crash.html
@@ -14,7 +14,7 @@
         testRunner.dumpAsText();
 
     leftSquare.addEventListener('mousedown', function() { leftSquare.parentNode.appendChild(leftSquare); });
-    leftSquare.addEventListener('mousedown', function() { leftSquare.instanceRoot.correspondingElement.setAttribute("fill", "green"); });
+    leftSquare.addEventListener('mousedown', function() { document.getElementById("square").setAttribute("fill", "green"); });
 
     if (window.eventSender) {
         eventSender.mouseMoveTo(20, 20);
@@ -25,4 +25,4 @@
 <p>Test re-appending a use node with multiple event listeners, triggered by the first listener.
   If running manually, click on the left square.
   Pass if no crash and the visible result is an orange square left of a green square.</p>
-</html>
+</html>