diff --git a/layout/base/nsChildIterator.cpp b/layout/base/nsChildIterator.cpp
new file mode 100644
index 000000000000..7ae0a7a865b1
--- /dev/null
+++ b/layout/base/nsChildIterator.cpp
@@ -0,0 +1,82 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+// vim:cindent:ts=2:et:sw=2:
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: NPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Netscape Public License
+ * Version 1.1 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/NPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is mozilla.org code.
+ *
+ * The Initial Developer of the Original Code is 
+ * Netscape Communications Corporation.
+ * Portions created by the Initial Developer are Copyright (C) 1998
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or 
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the NPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the NPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#include "nsChildIterator.h"
+#include "nsIDocument.h"
+#include "nsIBindingManager.h"
+
+nsresult
+ChildIterator::Init(nsIContent*    aContent,
+                    ChildIterator* aFirst,
+                    ChildIterator* aLast)
+{
+  NS_PRECONDITION(aContent != nsnull, "no content");
+  if (! aContent)
+    return NS_ERROR_NULL_POINTER;
+
+  nsCOMPtr<nsIDocument> doc;
+  aContent->GetDocument(*getter_AddRefs(doc));
+  NS_ASSERTION(doc != nsnull, "element not in the document");
+  if (! doc)
+    return NS_ERROR_FAILURE;
+
+  nsCOMPtr<nsIBindingManager> mgr;
+  doc->GetBindingManager(getter_AddRefs(mgr));
+  if (! mgr)
+    return NS_ERROR_FAILURE;
+
+  // If this node has XBL children, then use them. Otherwise, just use
+  // the vanilla content APIs.
+  nsCOMPtr<nsIDOMNodeList> nodes;
+  mgr->GetXBLChildNodesFor(aContent, getter_AddRefs(nodes));
+
+  PRUint32 length;
+  if (nodes)
+    nodes->GetLength(&length);
+  else
+    aContent->ChildCount((PRInt32&) length);
+
+  aFirst->mContent = aContent;
+  aLast->mContent  = aContent;
+  aFirst->mIndex   = 0;
+  aLast->mIndex    = length;
+  aFirst->mNodes   = nodes;
+  aLast->mNodes    = nodes;
+
+  return NS_OK;
+}
diff --git a/layout/base/nsChildIterator.h b/layout/base/nsChildIterator.h
new file mode 100644
index 000000000000..18411fb3d1fb
--- /dev/null
+++ b/layout/base/nsChildIterator.h
@@ -0,0 +1,145 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+// vim:cindent:ts=2:et:sw=2:
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: NPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Netscape Public License
+ * Version 1.1 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/NPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is mozilla.org code.
+ *
+ * The Initial Developer of the Original Code is 
+ * Netscape Communications Corporation.
+ * Portions created by the Initial Developer are Copyright (C) 1998
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or 
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the NPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the NPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#include "nsCOMPtr.h"
+#include "nsIContent.h"
+#include "nsIDOMNodeList.h"
+#include "nsIDOMNode.h"
+
+/**
+ * Helper class for iterating children during frame construction.
+ * This class should always be used in lieu of the straight content
+ * node APIs, since it handles XBL-generated anonymous content as
+ * well.
+ */
+class ChildIterator
+{
+protected:
+  nsCOMPtr<nsIContent> mContent;
+  PRUint32 mIndex;
+  nsCOMPtr<nsIDOMNodeList> mNodes;
+
+public:
+  ChildIterator()
+    : mIndex(0) {}
+
+  ChildIterator(const ChildIterator& aOther)
+    : mContent(aOther.mContent),
+      mIndex(aOther.mIndex),
+      mNodes(aOther.mNodes) {}
+
+  ChildIterator& operator=(const ChildIterator& aOther) {
+    mContent = aOther.mContent;
+    mIndex = aOther.mIndex;
+    mNodes = aOther.mNodes;
+    return *this;
+  }
+
+  ChildIterator& operator++() {
+    ++mIndex;
+    return *this;
+  }
+
+  ChildIterator operator++(int) {
+    ChildIterator result(*this);
+    ++mIndex;
+    return result;
+  }
+
+  ChildIterator& operator--() {
+    --mIndex;
+    return *this;
+  }
+
+  ChildIterator operator--(int) {
+    ChildIterator result(*this);
+    --mIndex;
+    return result;
+  }
+
+  already_AddRefed<nsIContent> get() const {
+    nsIContent* result = nsnull;
+    if (mNodes) {
+      nsCOMPtr<nsIDOMNode> node;
+      mNodes->Item(mIndex, getter_AddRefs(node));
+      CallQueryInterface(node, &result);
+    }
+    else 
+      mContent->ChildAt(PRInt32(mIndex), result);
+
+    return result;
+  }
+
+  already_AddRefed<nsIContent> operator*() const { return get(); }
+
+  PRBool operator==(const ChildIterator& aOther) const {
+    return mContent == aOther.mContent && mIndex == aOther.mIndex;
+  }
+
+  PRBool operator!=(const ChildIterator& aOther) const {
+    return !aOther.operator==(*this);
+  }
+
+  PRUint32 index() {
+    return mIndex;
+  }
+
+  void seek(PRUint32 aIndex) {
+#ifdef DEBUG
+    // Make sure that aIndex is reasonable
+    PRUint32 length;
+    if (mNodes)
+      mNodes->GetLength(&length);
+    else
+      mContent->ChildCount(NS_REINTERPRET_CAST(PRInt32&, length));
+
+    NS_ASSERTION(PRInt32(aIndex) >= 0 && aIndex <= length, "out of bounds");
+#endif
+
+    mIndex = aIndex;
+  }
+
+  /**
+   * Create a pair of ChildIterators for a content node. aFirst will
+   * point to the first child of aContent; aLast will point one past
+   * the last child of aContent.
+   */
+  static nsresult Init(nsIContent*    aContent,
+                       ChildIterator* aFirst,
+                       ChildIterator* aLast);
+};
diff --git a/layout/html/style/src/nsChildIterator.cpp b/layout/html/style/src/nsChildIterator.cpp
new file mode 100644
index 000000000000..7ae0a7a865b1
--- /dev/null
+++ b/layout/html/style/src/nsChildIterator.cpp
@@ -0,0 +1,82 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+// vim:cindent:ts=2:et:sw=2:
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: NPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Netscape Public License
+ * Version 1.1 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/NPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is mozilla.org code.
+ *
+ * The Initial Developer of the Original Code is 
+ * Netscape Communications Corporation.
+ * Portions created by the Initial Developer are Copyright (C) 1998
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or 
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the NPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the NPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#include "nsChildIterator.h"
+#include "nsIDocument.h"
+#include "nsIBindingManager.h"
+
+nsresult
+ChildIterator::Init(nsIContent*    aContent,
+                    ChildIterator* aFirst,
+                    ChildIterator* aLast)
+{
+  NS_PRECONDITION(aContent != nsnull, "no content");
+  if (! aContent)
+    return NS_ERROR_NULL_POINTER;
+
+  nsCOMPtr<nsIDocument> doc;
+  aContent->GetDocument(*getter_AddRefs(doc));
+  NS_ASSERTION(doc != nsnull, "element not in the document");
+  if (! doc)
+    return NS_ERROR_FAILURE;
+
+  nsCOMPtr<nsIBindingManager> mgr;
+  doc->GetBindingManager(getter_AddRefs(mgr));
+  if (! mgr)
+    return NS_ERROR_FAILURE;
+
+  // If this node has XBL children, then use them. Otherwise, just use
+  // the vanilla content APIs.
+  nsCOMPtr<nsIDOMNodeList> nodes;
+  mgr->GetXBLChildNodesFor(aContent, getter_AddRefs(nodes));
+
+  PRUint32 length;
+  if (nodes)
+    nodes->GetLength(&length);
+  else
+    aContent->ChildCount((PRInt32&) length);
+
+  aFirst->mContent = aContent;
+  aLast->mContent  = aContent;
+  aFirst->mIndex   = 0;
+  aLast->mIndex    = length;
+  aFirst->mNodes   = nodes;
+  aLast->mNodes    = nodes;
+
+  return NS_OK;
+}
diff --git a/layout/html/style/src/nsChildIterator.h b/layout/html/style/src/nsChildIterator.h
new file mode 100644
index 000000000000..18411fb3d1fb
--- /dev/null
+++ b/layout/html/style/src/nsChildIterator.h
@@ -0,0 +1,145 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+// vim:cindent:ts=2:et:sw=2:
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: NPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Netscape Public License
+ * Version 1.1 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/NPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is mozilla.org code.
+ *
+ * The Initial Developer of the Original Code is 
+ * Netscape Communications Corporation.
+ * Portions created by the Initial Developer are Copyright (C) 1998
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or 
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the NPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the NPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#include "nsCOMPtr.h"
+#include "nsIContent.h"
+#include "nsIDOMNodeList.h"
+#include "nsIDOMNode.h"
+
+/**
+ * Helper class for iterating children during frame construction.
+ * This class should always be used in lieu of the straight content
+ * node APIs, since it handles XBL-generated anonymous content as
+ * well.
+ */
+class ChildIterator
+{
+protected:
+  nsCOMPtr<nsIContent> mContent;
+  PRUint32 mIndex;
+  nsCOMPtr<nsIDOMNodeList> mNodes;
+
+public:
+  ChildIterator()
+    : mIndex(0) {}
+
+  ChildIterator(const ChildIterator& aOther)
+    : mContent(aOther.mContent),
+      mIndex(aOther.mIndex),
+      mNodes(aOther.mNodes) {}
+
+  ChildIterator& operator=(const ChildIterator& aOther) {
+    mContent = aOther.mContent;
+    mIndex = aOther.mIndex;
+    mNodes = aOther.mNodes;
+    return *this;
+  }
+
+  ChildIterator& operator++() {
+    ++mIndex;
+    return *this;
+  }
+
+  ChildIterator operator++(int) {
+    ChildIterator result(*this);
+    ++mIndex;
+    return result;
+  }
+
+  ChildIterator& operator--() {
+    --mIndex;
+    return *this;
+  }
+
+  ChildIterator operator--(int) {
+    ChildIterator result(*this);
+    --mIndex;
+    return result;
+  }
+
+  already_AddRefed<nsIContent> get() const {
+    nsIContent* result = nsnull;
+    if (mNodes) {
+      nsCOMPtr<nsIDOMNode> node;
+      mNodes->Item(mIndex, getter_AddRefs(node));
+      CallQueryInterface(node, &result);
+    }
+    else 
+      mContent->ChildAt(PRInt32(mIndex), result);
+
+    return result;
+  }
+
+  already_AddRefed<nsIContent> operator*() const { return get(); }
+
+  PRBool operator==(const ChildIterator& aOther) const {
+    return mContent == aOther.mContent && mIndex == aOther.mIndex;
+  }
+
+  PRBool operator!=(const ChildIterator& aOther) const {
+    return !aOther.operator==(*this);
+  }
+
+  PRUint32 index() {
+    return mIndex;
+  }
+
+  void seek(PRUint32 aIndex) {
+#ifdef DEBUG
+    // Make sure that aIndex is reasonable
+    PRUint32 length;
+    if (mNodes)
+      mNodes->GetLength(&length);
+    else
+      mContent->ChildCount(NS_REINTERPRET_CAST(PRInt32&, length));
+
+    NS_ASSERTION(PRInt32(aIndex) >= 0 && aIndex <= length, "out of bounds");
+#endif
+
+    mIndex = aIndex;
+  }
+
+  /**
+   * Create a pair of ChildIterators for a content node. aFirst will
+   * point to the first child of aContent; aLast will point one past
+   * the last child of aContent.
+   */
+  static nsresult Init(nsIContent*    aContent,
+                       ChildIterator* aFirst,
+                       ChildIterator* aLast);
+};