diff -r 000000000000 -r 6474c204b198 layout/xul/nsListBoxObject.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/xul/nsListBoxObject.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,211 @@
+/* -*- 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 "nsCOMPtr.h"
+#include "nsPIListBoxObject.h"
+#include "nsBoxObject.h"
+#include "nsIFrame.h"
+#include "nsBindingManager.h"
+#include "nsIDOMElement.h"
+#include "nsIDOMNodeList.h"
+#include "nsGkAtoms.h"
+#include "nsIScrollableFrame.h"
+#include "nsListBoxBodyFrame.h"
+#include "ChildIterator.h"
+
+class nsListBoxObject : public nsPIListBoxObject, public nsBoxObject
+{
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSILISTBOXOBJECT
+
+  // nsPIListBoxObject
+  virtual nsListBoxBodyFrame* GetListBoxBody(bool aFlush) MOZ_OVERRIDE;
+
+  nsListBoxObject();
+
+  // nsPIBoxObject
+  virtual void Clear() MOZ_OVERRIDE;
+  virtual void ClearCachedValues() MOZ_OVERRIDE;
+  
+protected:
+  nsListBoxBodyFrame *mListBoxBody;
+};
+
+NS_IMPL_ISUPPORTS_INHERITED(nsListBoxObject, nsBoxObject, nsIListBoxObject,
+                            nsPIListBoxObject)
+
+nsListBoxObject::nsListBoxObject()
+  : mListBoxBody(nullptr)
+{
+}
+
+//////////////////////////////////////////////////////////////////////////
+//// nsIListBoxObject
+
+NS_IMETHODIMP
+nsListBoxObject::GetRowCount(int32_t *aResult)
+{
+  nsListBoxBodyFrame* body = GetListBoxBody(true);
+  if (body)
+    return body->GetRowCount(aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsListBoxObject::GetNumberOfVisibleRows(int32_t *aResult)
+{
+  nsListBoxBodyFrame* body = GetListBoxBody(true);
+  if (body)
+    return body->GetNumberOfVisibleRows(aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsListBoxObject::GetIndexOfFirstVisibleRow(int32_t *aResult)
+{
+  nsListBoxBodyFrame* body = GetListBoxBody(true);
+  if (body)
+    return body->GetIndexOfFirstVisibleRow(aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsListBoxObject::EnsureIndexIsVisible(int32_t aRowIndex)
+{
+  nsListBoxBodyFrame* body = GetListBoxBody(true);
+  if (body)
+    return body->EnsureIndexIsVisible(aRowIndex);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsListBoxObject::ScrollToIndex(int32_t aRowIndex)
+{
+  nsListBoxBodyFrame* body = GetListBoxBody(true);
+  if (body)
+    return body->ScrollToIndex(aRowIndex);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsListBoxObject::ScrollByLines(int32_t aNumLines)
+{
+  nsListBoxBodyFrame* body = GetListBoxBody(true);
+  if (body)
+    return body->ScrollByLines(aNumLines);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsListBoxObject::GetItemAtIndex(int32_t index, nsIDOMElement **_retval)
+{
+  nsListBoxBodyFrame* body = GetListBoxBody(true);
+  if (body)
+    return body->GetItemAtIndex(index, _retval);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsListBoxObject::GetIndexOfItem(nsIDOMElement* aElement, int32_t *aResult)
+{
+  *aResult = 0;
+
+  nsListBoxBodyFrame* body = GetListBoxBody(true);
+  if (body)
+    return body->GetIndexOfItem(aElement, aResult);
+  return NS_OK;
+}
+
+//////////////////////
+
+static nsIContent*
+FindBodyContent(nsIContent* aParent)
+{
+  if (aParent->Tag() == nsGkAtoms::listboxbody) {
+    return aParent;
+  }
+
+  mozilla::dom::FlattenedChildIterator iter(aParent);
+  for (nsIContent* child = iter.GetNextChild(); child; child = iter.GetNextChild()) {
+    nsIContent* result = FindBodyContent(child);
+    if (result) {
+      return result;
+    }
+  }
+
+  return nullptr;
+}
+
+nsListBoxBodyFrame*
+nsListBoxObject::GetListBoxBody(bool aFlush)
+{
+  if (mListBoxBody) {
+    return mListBoxBody;
+  }
+
+  nsIPresShell* shell = GetPresShell(false);
+  if (!shell) {
+    return nullptr;
+  }
+
+  nsIFrame* frame = aFlush ? 
+                      GetFrame(false) /* does Flush_Frames */ :
+                      mContent->GetPrimaryFrame();
+  if (!frame)
+    return nullptr;
+
+  // Iterate over our content model children looking for the body.
+  nsCOMPtr<nsIContent> content = FindBodyContent(frame->GetContent());
+
+  if (!content)
+    return nullptr;
+
+  // this frame will be a nsGFXScrollFrame
+  frame = content->GetPrimaryFrame();
+  if (!frame)
+     return nullptr;
+  nsIScrollableFrame* scrollFrame = do_QueryFrame(frame);
+  if (!scrollFrame)
+    return nullptr;
+
+  // this frame will be the one we want
+  nsIFrame* yeahBaby = scrollFrame->GetScrolledFrame();
+  if (!yeahBaby)
+     return nullptr;
+
+  // It's a frame. Refcounts are irrelevant.
+  nsListBoxBodyFrame* listBoxBody = do_QueryFrame(yeahBaby);
+  NS_ENSURE_TRUE(listBoxBody &&
+                 listBoxBody->SetBoxObject(this),
+                 nullptr);
+  mListBoxBody = listBoxBody;
+  return mListBoxBody;
+}
+
+void
+nsListBoxObject::Clear()
+{
+  ClearCachedValues();
+
+  nsBoxObject::Clear();
+}
+
+void
+nsListBoxObject::ClearCachedValues()
+{
+  mListBoxBody = nullptr;
+}
+
+// Creation Routine ///////////////////////////////////////////////////////////////////////
+
+nsresult
+NS_NewListBoxObject(nsIBoxObject** aResult)
+{
+  *aResult = new nsListBoxObject;
+  if (!*aResult)
+    return NS_ERROR_OUT_OF_MEMORY;
+  NS_ADDREF(*aResult);
+  return NS_OK;
+}