Fix clusterfuzz crash

Bug: 1059187
Change-Id: I6d42d40d5d6971ddba41c2fe62cb39e7b1e1b9f9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2092431Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#747955}

third_party/blink/renderer/modules/accessibility/ax_layout_object.cc

@@ -2525,7 +2525,7 @@ bool AXLayoutObject::IsDataTable() const {
       }
 
       LayoutObject* cell_layout_object = cell->GetLayoutObject();
-      if (!cell_layout_object)
+      if (!cell_layout_object || !cell_layout_object->IsLayoutBlock())
         continue;
 
       const LayoutBlock* cell_layout_block =