(iOS) Dragging the selection in Live Text far away sometimes causes a…

… crash

https://bugs.webkit.org/show_bug.cgi?id=255566
rdar://108169157

Reviewed by Wenson Hsieh.

When selecting text with Live Text, if the selection contains different writing modes, a crash
can occur when collecting the selection geometries if the ancestor does not have a renderer.

This PR fixes this by adding a null check for the existence of a renderer.

* Source/WebCore/rendering/RenderObject.cpp:
(WebCore::RenderObject::collectSelectionGeometriesInternal):

Canonical link: https://commits.webkit.org/263053@main

Source/WebCore/rendering/RenderObject.cpp

@@ -2410,8 +2410,10 @@ auto RenderObject::collectSelectionGeometriesInternal(const SimpleRange& range)
     // The range could span nodes with different writing modes.
     // If this is the case, we use the writing mode of the common ancestor.
     if (containsDifferentWritingModes) {
-        if (auto ancestor = commonInclusiveAncestor<ComposedTree>(range))
-            hasFlippedWritingMode = ancestor->renderer()->style().isFlippedBlocksWritingMode();
+        if (auto ancestor = commonInclusiveAncestor<ComposedTree>(range)) {
+            if (auto* renderer = ancestor->renderer())
+                hasFlippedWritingMode = renderer->style().isFlippedBlocksWritingMode();
+        }
     }
 
     auto numberOfGeometries = geometries.size();