diff -r 000000000000 -r 6474c204b198 editor/libeditor/base/InsertElementTxn.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/editor/libeditor/base/InsertElementTxn.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,106 @@
+/* -*- 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 <stdio.h>                      // for printf
+
+#include "InsertElementTxn.h"
+#include "nsAString.h"
+#include "nsDebug.h"                    // for NS_ENSURE_TRUE, etc
+#include "nsError.h"                    // for NS_ERROR_NULL_POINTER, etc
+#include "nsIContent.h"                 // for nsIContent
+#include "nsIEditor.h"                  // for nsIEditor
+#include "nsINode.h"                    // for nsINode
+#include "nsISelection.h"               // for nsISelection
+#include "nsMemory.h"                   // for nsMemory
+#include "nsReadableUtils.h"            // for ToNewCString
+#include "nsString.h"                   // for nsString
+
+InsertElementTxn::InsertElementTxn()
+  : EditTxn()
+{
+}
+
+NS_IMPL_CYCLE_COLLECTION_INHERITED(InsertElementTxn, EditTxn,
+                                   mNode,
+                                   mParent)
+
+NS_IMPL_ADDREF_INHERITED(InsertElementTxn, EditTxn)
+NS_IMPL_RELEASE_INHERITED(InsertElementTxn, EditTxn)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(InsertElementTxn)
+NS_INTERFACE_MAP_END_INHERITING(EditTxn)
+
+NS_IMETHODIMP InsertElementTxn::Init(nsIDOMNode *aNode,
+                                     nsIDOMNode *aParent,
+                                     int32_t     aOffset,
+                                     nsIEditor  *aEditor)
+{
+  NS_ASSERTION(aNode && aParent && aEditor, "bad arg");
+  NS_ENSURE_TRUE(aNode && aParent && aEditor, NS_ERROR_NULL_POINTER);
+
+  mNode = do_QueryInterface(aNode);
+  mParent = do_QueryInterface(aParent);
+  mOffset = aOffset;
+  mEditor = aEditor;
+  NS_ENSURE_TRUE(mNode && mParent && mEditor, NS_ERROR_INVALID_ARG);
+  return NS_OK;
+}
+
+
+NS_IMETHODIMP InsertElementTxn::DoTransaction(void)
+{
+  NS_ENSURE_TRUE(mNode && mParent, NS_ERROR_NOT_INITIALIZED);
+
+  nsCOMPtr<nsINode> parent = do_QueryInterface(mParent);
+  NS_ENSURE_STATE(parent);
+
+  uint32_t count = parent->GetChildCount();
+  if (mOffset > int32_t(count) || mOffset == -1) {
+    // -1 is sentinel value meaning "append at end"
+    mOffset = count;
+  }
+
+  nsCOMPtr<nsIContent> refContent = parent->GetChildAt(mOffset);
+  // note, it's ok for refNode to be null.  that means append
+  nsCOMPtr<nsIDOMNode> refNode = refContent ? refContent->AsDOMNode() : nullptr;
+
+  mEditor->MarkNodeDirty(mNode);
+
+  nsCOMPtr<nsIDOMNode> resultNode;
+  nsresult result = mParent->InsertBefore(mNode, refNode, getter_AddRefs(resultNode));
+  NS_ENSURE_SUCCESS(result, result);
+  NS_ENSURE_TRUE(resultNode, NS_ERROR_NULL_POINTER);
+
+  // only set selection to insertion point if editor gives permission
+  bool bAdjustSelection;
+  mEditor->ShouldTxnSetSelection(&bAdjustSelection);
+  if (bAdjustSelection)
+  {
+    nsCOMPtr<nsISelection> selection;
+    result = mEditor->GetSelection(getter_AddRefs(selection));
+    NS_ENSURE_SUCCESS(result, result);
+    NS_ENSURE_TRUE(selection, NS_ERROR_NULL_POINTER);
+    // place the selection just after the inserted element
+    selection->Collapse(mParent, mOffset+1);
+  }
+  else
+  {
+    // do nothing - dom range gravity will adjust selection
+  }
+  return result;
+}
+
+NS_IMETHODIMP InsertElementTxn::UndoTransaction(void)
+{
+  NS_ENSURE_TRUE(mNode && mParent, NS_ERROR_NOT_INITIALIZED);
+
+  nsCOMPtr<nsIDOMNode> resultNode;
+  return mParent->RemoveChild(mNode, getter_AddRefs(resultNode));
+}
+
+NS_IMETHODIMP InsertElementTxn::GetTxnDescription(nsAString& aString)
+{
+  aString.AssignLiteral("InsertElementTxn");
+  return NS_OK;
+}