Eliminate a caller of deprecated ComputedStyle::ListStyleType()

Bug: 687225
Change-Id: Ic90fcd65d9e932f3a9916938af7595e121247280
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2629967
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Commit-Queue: Anders Hartvoll Ruud <andruud@chromium.org>
Auto-Submit: Xiaocheng Hu <xiaochengh@chromium.org>
Reviewed-by: Anders Hartvoll Ruud <andruud@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843850}

third_party/blink/renderer/core/layout/layout_object.cc

@@ -632,9 +632,12 @@ bool LayoutObject::IsListMarkerForSummary() const {
           DynamicTo<HTMLSummaryElement>(Parent()->GetNode())) {
     if (!summary->IsMainSummary())
       return false;
-    const auto type = StyleRef().ListStyleType();
-    return type == EListStyleType::kDisclosureOpen ||
-           type == EListStyleType::kDisclosureClosed;
+    if (ListMarker::GetListStyleCategory(GetDocument(), StyleRef()) !=
+        ListMarker::ListStyleCategory::kSymbol)
+      return false;
+    const AtomicString& name =
+        StyleRef().GetListStyleType()->GetCounterStyleName();
+    return name == "disclosure-open" || name == "disclosure-closed";
   }
   return false;
 }