diff --git a/dom/base/nsContentUtils.cpp b/dom/base/nsContentUtils.cpp
index db8ea5fed7..adaf35920e 100644
--- a/dom/base/nsContentUtils.cpp
+++ b/dom/base/nsContentUtils.cpp
@@ -2395,34 +2395,35 @@ nsContentUtils::GetCommonAncestor(nsIDOMNode *aNode,
   return CallQueryInterface(common, aCommonAncestor);
 }
 
-// static
-nsINode*
-nsContentUtils::GetCommonAncestor(nsINode* aNode1,
-                                  nsINode* aNode2)
+template <typename Node, typename GetParentFunc>
+static Node*
+GetCommonAncestorInternal(Node* aNode1,
+                          Node* aNode2,
+                          GetParentFunc aGetParentFunc)
 {
   if (aNode1 == aNode2) {
     return aNode1;
   }
 
   // Build the chain of parents
-  AutoTArray<nsINode*, 30> parents1, parents2;
+  AutoTArray<Node*, 30> parents1, parents2;
   do {
     parents1.AppendElement(aNode1);
-    aNode1 = aNode1->GetParentNode();
+    aNode1 = aGetParentFunc(aNode1);
   } while (aNode1);
   do {
     parents2.AppendElement(aNode2);
-    aNode2 = aNode2->GetParentNode();
+    aNode2 = aGetParentFunc(aNode2);
   } while (aNode2);
 
   // Find where the parent chain differs
   uint32_t pos1 = parents1.Length();
   uint32_t pos2 = parents2.Length();
-  nsINode* parent = nullptr;
+  Node* parent = nullptr;
   uint32_t len;
   for (len = std::min(pos1, pos2); len > 0; --len) {
-    nsINode* child1 = parents1.ElementAt(--pos1);
-    nsINode* child2 = parents2.ElementAt(--pos2);
+    Node* child1 = parents1.ElementAt(--pos1);
+    Node* child2 = parents2.ElementAt(--pos2);
     if (child1 != child2) {
       break;
     }
@@ -2432,6 +2433,15 @@ nsContentUtils::GetCommonAncestor(nsINode* aNode1,
   return parent;
 }
 
+/* static */
+nsINode*
+nsContentUtils::GetCommonAncestor(nsINode* aNode1, nsINode* aNode2)
+{
+  return GetCommonAncestorInternal(aNode1, aNode2, [](nsINode* aNode) {
+    return aNode->GetParentNode();
+  });
+}
+
 // static
 nsINode*
 nsContentUtils::GetCommonAncestorUnderInteractiveContent(nsINode* aNode1,
diff --git a/dom/base/nsContentUtils.h b/dom/base/nsContentUtils.h
index 74239c8036..c6e8070576 100644
--- a/dom/base/nsContentUtils.h
+++ b/dom/base/nsContentUtils.h
@@ -333,11 +333,10 @@ public:
                                     nsIDOMNode** aCommonAncestor);
 
   /**
-   * Returns the common ancestor, if any, for two nodes. Returns null if the
-   * nodes are disconnected.
+   * Returns the common ancestor, if any, for two nodes.
+   * Returns null if the nodes are disconnected.
    */
-  static nsINode* GetCommonAncestor(nsINode* aNode1,
-                                    nsINode* aNode2);
+  static nsINode* GetCommonAncestor(nsINode* aNode1, nsINode* aNode2);
 
   /**
    * Returns the common ancestor under interactive content, if any.