diff -r 000000000000 -r 6474c204b198 layout/xul/grid/nsGridRowLayout.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/xul/grid/nsGridRowLayout.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,193 @@
+/* -*- 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/. */
+
+//
+// Eric Vaughan
+// Netscape Communications
+//
+// See documentation in associated header file
+//
+
+#include "nsGridRowLayout.h"
+#include "nsBoxLayoutState.h"
+#include "nsIScrollableFrame.h"
+#include "nsBox.h"
+#include "nsStackLayout.h"
+#include "nsGrid.h"
+
+nsGridRowLayout::nsGridRowLayout():nsSprocketLayout()
+{
+}
+
+void
+nsGridRowLayout::ChildrenInserted(nsIFrame* aBox, nsBoxLayoutState& aState,
+                                  nsIFrame* aPrevBox,
+                                  const nsFrameList::Slice& aNewChildren)
+{
+  ChildAddedOrRemoved(aBox, aState);
+}
+
+void
+nsGridRowLayout::ChildrenAppended(nsIFrame* aBox, nsBoxLayoutState& aState,
+                                  const nsFrameList::Slice& aNewChildren)
+{
+  ChildAddedOrRemoved(aBox, aState);
+}
+
+void
+nsGridRowLayout::ChildrenRemoved(nsIFrame* aBox, nsBoxLayoutState& aState, nsIFrame* aChildList)
+{
+  ChildAddedOrRemoved(aBox, aState);
+}
+
+void
+nsGridRowLayout::ChildrenSet(nsIFrame* aBox, nsBoxLayoutState& aState, nsIFrame* aChildList)
+{
+  ChildAddedOrRemoved(aBox, aState);
+}
+
+nsIGridPart*
+nsGridRowLayout::GetParentGridPart(nsIFrame* aBox, nsIFrame** aParentBox)
+{
+  // go up and find our parent gridRow. Skip and non gridRow
+  // parents.
+  *aParentBox = nullptr;
+  
+  // walk up through any scrollboxes
+  aBox = nsGrid::GetScrollBox(aBox);
+
+  // get the parent
+  if (aBox)
+    aBox = aBox->GetParentBox();
+
+  if (aBox)
+  {
+    nsIGridPart* parentGridRow = nsGrid::GetPartFromBox(aBox);
+    if (parentGridRow && parentGridRow->CanContain(this)) {
+      *aParentBox = aBox;
+      return parentGridRow;
+    }
+  }
+
+  return nullptr;
+}
+
+
+nsGrid*
+nsGridRowLayout::GetGrid(nsIFrame* aBox, int32_t* aIndex, nsGridRowLayout* aRequestor)
+{
+
+   if (aRequestor == nullptr)
+   {
+      nsIFrame* parentBox; // nsIFrame is implemented by nsIFrame and is not refcounted.
+      nsIGridPart* parent = GetParentGridPart(aBox, &parentBox);
+      if (parent)
+         return parent->GetGrid(parentBox, aIndex, this);
+      return nullptr;
+   }
+
+   int32_t index = -1;
+   nsIFrame* child = aBox->GetChildBox();
+   int32_t count = 0;
+   while(child)
+   {
+     // if there is a scrollframe walk inside it to its child
+     nsIFrame* childBox = nsGrid::GetScrolledBox(child);
+
+     nsBoxLayout* layout = childBox->GetLayoutManager();
+     nsIGridPart* gridRow = nsGrid::GetPartFromBox(childBox);
+     if (gridRow) 
+     {
+       if (layout == aRequestor) {
+          index = count;
+          break;
+       }
+       count += gridRow->GetRowCount();
+     } else 
+       count++;
+
+     child = child->GetNextBox();
+   }
+
+   // if we didn't find ourselves then the tree isn't properly formed yet
+   // this could happen during initial construction so lets just
+   // fail.
+   if (index == -1) {
+     *aIndex = -1;
+     return nullptr;
+   }
+
+   (*aIndex) += index;
+
+   nsIFrame* parentBox; // nsIFrame is implemented by nsIFrame and is not refcounted.
+   nsIGridPart* parent = GetParentGridPart(aBox, &parentBox);
+   if (parent)
+     return parent->GetGrid(parentBox, aIndex, this);
+
+   return nullptr;
+}
+
+nsMargin
+nsGridRowLayout::GetTotalMargin(nsIFrame* aBox, bool aIsHorizontal)
+{
+  // get our parents margin
+  nsMargin margin(0,0,0,0);
+  nsIFrame* parent = nullptr;
+  nsIGridPart* part = GetParentGridPart(aBox, &parent);
+  if (part && parent) {
+    // if we are the first or last child walk upward and add margins.
+
+    // make sure we check for a scrollbox
+    aBox = nsGrid::GetScrollBox(aBox);
+
+    // see if we have a next to see if we are last
+    nsIFrame* next = aBox->GetNextBox();
+
+    // get the parent first child to see if we are first
+    nsIFrame* child = parent->GetChildBox();
+
+    margin = part->GetTotalMargin(parent, aIsHorizontal);
+
+    // if first or last
+    if (child == aBox || next == nullptr) {
+
+       // if it's not the first child remove the top margin
+       // we don't need it.
+       if (child != aBox)
+       {
+          if (aIsHorizontal)
+              margin.top = 0;
+          else 
+              margin.left = 0;
+       }
+
+       // if it's not the last child remove the bottom margin
+       // we don't need it.
+       if (next != nullptr)
+       {
+          if (aIsHorizontal)
+              margin.bottom = 0;
+          else 
+              margin.right = 0;
+       }
+
+    }
+  }
+    
+  // add ours to it.
+  nsMargin ourMargin;
+  aBox->GetMargin(ourMargin);
+  margin += ourMargin;
+
+  return margin;
+}
+
+NS_IMPL_ADDREF_INHERITED(nsGridRowLayout, nsBoxLayout)
+NS_IMPL_RELEASE_INHERITED(nsGridRowLayout, nsBoxLayout)
+
+NS_INTERFACE_MAP_BEGIN(nsGridRowLayout)
+  NS_INTERFACE_MAP_ENTRY(nsIGridPart)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIGridPart)
+NS_INTERFACE_MAP_END_INHERITING(nsBoxLayout)