servo: Merge #9799 - Fix step 14.2 of Range::ExtractContents (from nox:range-extractcontents); r=KiChjang

We need the last inclusive ancestor of start node that is not an inclusive ancestor
of end node, not the first that is an inclusive ancestor of it.

Source-Repo: https://github.com/servo/servo
Source-Revision: dfdeabf57df02cf4b8a878b3b9933a08d156082d

servo/components/script/dom/range.rs

@@ -564,8 +564,9 @@ impl RangeMethods for Range {
         } else {
             // Step 14.1-2.
             let reference_node = start_node.ancestors()
-                                           .find(|n| n.is_inclusive_ancestor_of(end_node.r()))
-                                           .unwrap();
+                                           .take_while(|n| !n.is_inclusive_ancestor_of(&end_node))
+                                           .last()
+                                           .unwrap_or(Root::from_ref(&start_node));
             // Step 14.3.
             (reference_node.GetParentNode().unwrap(), reference_node.index() + 1)
         };