Prevent crash when scrolling for find-in-page

The clusterfuzz test case is very large and complicated, so I wasn't
able to reproduce the test case in a normal/minimal page. From debugging
while using the clusterfuzz repro tool, all I can tell is that
find-in-page is trying to scroll to the "Choose File" text node inside
an <input type=file>, and that it doesn't have a LayoutObject for some
reason, despite being attached to the document and the call to
UpdateStyleAndLayoutForNode in the previous block being run.

Bug: 1129341
Change-Id: I6de3eac626899ab15c157150ed5015119c497876
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2419154
Commit-Queue: Joey Arhar <jarhar@chromium.org>
Reviewed-by: vmpstr <vmpstr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808552}

third_party/blink/renderer/core/editing/finder/text_finder.cc

@@ -104,6 +104,12 @@ static void ScrollToVisible(Range* match) {
     first_node.GetDocument().UpdateStyleAndLayoutForNode(
         &first_node, DocumentUpdateReason::kFindInPage);
   }
+
+  // We don't always have a LayoutObject for the node we're trying to scroll to
+  // after the async step: crbug.com/1129341
+  if (!first_node.GetLayoutObject())
+    return;
+
   Settings* settings = first_node.GetDocument().GetSettings();
   bool smooth_find_enabled =
       settings ? settings->GetSmoothScrollForFindEnabled() : false;