diff -r 000000000000 -r 6474c204b198 editor/txmgr/src/nsTransactionStack.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/editor/txmgr/src/nsTransactionStack.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,96 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsAutoPtr.h"
+#include "nsCOMPtr.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsISupportsUtils.h"
+#include "nsTransactionItem.h"
+#include "nsTransactionStack.h"
+#include "nscore.h"
+
+nsTransactionStack::nsTransactionStack(nsTransactionStack::Type aType)
+  : mType(aType)
+{
+}
+
+nsTransactionStack::~nsTransactionStack()
+{
+  Clear();
+}
+
+void
+nsTransactionStack::Push(nsTransactionItem *aTransaction)
+{
+  if (!aTransaction) {
+    return;
+  }
+
+  // The stack's bottom is the front of the deque, and the top is the back.
+  mDeque.push_back(aTransaction);
+}
+
+already_AddRefed<nsTransactionItem>
+nsTransactionStack::Pop()
+{
+  if (mDeque.empty()) {
+    return nullptr;
+  }
+  nsRefPtr<nsTransactionItem> ret = mDeque.back().forget();
+  mDeque.pop_back();
+  return ret.forget();
+}
+
+already_AddRefed<nsTransactionItem>
+nsTransactionStack::PopBottom()
+{
+  if (mDeque.empty()) {
+    return nullptr;
+  }
+  nsRefPtr<nsTransactionItem> ret = mDeque.front().forget();
+  mDeque.pop_front();
+  return ret.forget();
+}
+
+already_AddRefed<nsTransactionItem>
+nsTransactionStack::Peek()
+{
+  if (mDeque.empty()) {
+    return nullptr;
+  }
+  nsRefPtr<nsTransactionItem> ret = mDeque.back();
+  return ret.forget();
+}
+
+already_AddRefed<nsTransactionItem>
+nsTransactionStack::GetItem(int32_t aIndex)
+{
+  if (aIndex < 0 || aIndex >= static_cast<int32_t>(mDeque.size())) {
+    return nullptr;
+  }
+  nsRefPtr<nsTransactionItem> ret = mDeque[aIndex];
+  return ret.forget();
+}
+
+void
+nsTransactionStack::Clear()
+{
+  while (!mDeque.empty()) {
+    nsRefPtr<nsTransactionItem> tx = mType == FOR_UNDO ? Pop() : PopBottom();
+  };
+}
+
+void
+nsTransactionStack::DoTraverse(nsCycleCollectionTraversalCallback &cb)
+{
+  int32_t size = mDeque.size();
+  for (int32_t i = 0; i < size; ++i) {
+    nsTransactionItem* item = mDeque[i];
+    if (item) {
+      NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "transaction stack mDeque[i]");
+      cb.NoteNativeChild(item, NS_CYCLE_COLLECTION_PARTICIPANT(nsTransactionItem));
+    }
+  }
+}