Add frame check in TextFinder::FinishCurrentScopingEffort

This function might be called after the frame is removed now.

Bug: 1064683
Change-Id: I3092d2f77eeb0652c072277b9724fe4191e2e580
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2120777Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Commit-Queue: Rakina Zata Amni <rakina@chromium.org>
Cr-Commit-Position: refs/heads/master@{#753530}

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

@@ -456,11 +456,14 @@ void TextFinder::UpdateMatches(int identifier,
 }
 
 void TextFinder::FinishCurrentScopingEffort(int identifier) {
+  scoping_in_progress_ = false;
+  if (!OwnerFrame().GetFrame())
+    return;
+
   if (!total_match_count_)
     OwnerFrame().GetFrame()->Selection().Clear();
 
   FlushCurrentScopingEffort(identifier);
-  scoping_in_progress_ = false;
   // This frame is done, so show any scrollbar tickmarks we haven't drawn yet.
   InvalidatePaintForTickmarks();
 }