--- a/editor/libeditor/html/nsHTMLEditor.h
+++ b/editor/libeditor/html/nsHTMLEditor.h
@@ -658,21 +658,20 @@ protected:
   /* increase/decrease the font size of selection */
   nsresult RelativeFontChange( PRInt32 aSizeChange);
   
   /* helper routines for font size changing */
   nsresult RelativeFontChangeOnTextNode( PRInt32 aSizeChange, 
                                          nsIDOMCharacterData *aTextNode, 
                                          PRInt32 aStartOffset,
                                          PRInt32 aEndOffset);
+  nsresult RelativeFontChangeOnNode(PRInt32 aSizeChange, nsINode* aNode);
   nsresult RelativeFontChangeOnNode( PRInt32 aSizeChange, 
                                      nsIDOMNode *aNode);
   nsresult RelativeFontChangeHelper(PRInt32 aSizeChange, nsINode* aNode);
-  nsresult RelativeFontChangeHelper( PRInt32 aSizeChange, 
-                                     nsIDOMNode *aNode);
 
   /* helper routines for inline style */
   nsresult SetInlinePropertyOnTextNode( nsIDOMCharacterData *aTextNode, 
                                         PRInt32 aStartOffset,
                                         PRInt32 aEndOffset,
                                         nsIAtom *aProperty, 
                                         const nsAString *aAttribute,
                                         const nsAString *aValue);

--- a/editor/libeditor/html/nsHTMLEditorStyle.cpp
+++ b/editor/libeditor/html/nsHTMLEditorStyle.cpp
@@ -1662,27 +1662,16 @@ nsHTMLEditor::RelativeFontChangeOnTextNo
   
   // else reparent the node inside font node with appropriate relative size
   res = InsertContainerAbove(node, address_of(tmp), nodeType);
   return res;
 }
 
 
 nsresult
-nsHTMLEditor::RelativeFontChangeHelper(PRInt32 aSizeChange, nsIDOMNode* aNode)
-{
-  NS_ENSURE_TRUE(aNode, NS_ERROR_NULL_POINTER);
-
-  nsCOMPtr<nsINode> node = do_QueryInterface(aNode);
-  NS_ENSURE_STATE(node);
-
-  return RelativeFontChangeHelper(aSizeChange, node);
-}
-
-nsresult
 nsHTMLEditor::RelativeFontChangeHelper(PRInt32 aSizeChange, nsINode* aNode)
 {
   MOZ_ASSERT(aNode);
 
   /*  This routine looks for all the font nodes in the tree rooted by aNode,
       including aNode itself, looking for font nodes that have the size attr
       set.  Any such nodes need to have big or small put inside them, since
       they override any big/small that are above them.
@@ -1695,17 +1684,17 @@ nsHTMLEditor::RelativeFontChangeHelper(P
 
   // If this is a font node with size, put big/small inside it.
   if (aNode->IsElement() && aNode->AsElement()->IsHTML(nsGkAtoms::font) &&
       aNode->AsElement()->HasAttr(kNameSpaceID_None, nsGkAtoms::size)) {
     // Cycle through children and adjust relative font size.
     for (nsIContent* child = aNode->GetLastChild();
          child;
          child = child->GetPreviousSibling()) {
-      nsresult rv = RelativeFontChangeOnNode(aSizeChange, child->AsDOMNode());
+      nsresult rv = RelativeFontChangeOnNode(aSizeChange, child);
       NS_ENSURE_SUCCESS(rv, rv);
     }
   }
 
   // Now cycle through the children.
   for (nsIContent* child = aNode->GetLastChild();
        child;
        child = child->GetPreviousSibling()) {
@@ -1713,96 +1702,91 @@ nsHTMLEditor::RelativeFontChangeHelper(P
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
   return NS_OK;
 }
 
 
 nsresult
-nsHTMLEditor::RelativeFontChangeOnNode( PRInt32 aSizeChange, 
-                                        nsIDOMNode *aNode)
+nsHTMLEditor::RelativeFontChangeOnNode(PRInt32 aSizeChange,
+                                       nsIDOMNode* aNode)
 {
+  nsCOMPtr<nsINode> node = do_QueryInterface(aNode);
+  NS_ENSURE_TRUE(node, NS_ERROR_NULL_POINTER);
+
+  return RelativeFontChangeOnNode(aSizeChange, node);
+}
+
+nsresult
+nsHTMLEditor::RelativeFontChangeOnNode(PRInt32 aSizeChange, nsINode* aNode)
+{
+  MOZ_ASSERT(aNode);
   // Can only change font size by + or - 1
-  if ( !( (aSizeChange==1) || (aSizeChange==-1) ) )
+  if (aSizeChange != 1 && aSizeChange != -1) {
     return NS_ERROR_ILLEGAL_VALUE;
-  NS_ENSURE_TRUE(aNode, NS_ERROR_NULL_POINTER);
+  }
 
-  nsresult res = NS_OK;
-  nsCOMPtr<nsIDOMNode> tmp;
   nsIAtom* atom;
   if (aSizeChange == 1) {
     atom = nsGkAtoms::big;
   } else {
     atom = nsGkAtoms::small;
   }
   
-  // is it the opposite of what we want?  
-  if ( ((aSizeChange == 1) && nsHTMLEditUtils::IsSmall(aNode)) || 
-       ((aSizeChange == -1) &&  nsHTMLEditUtils::IsBig(aNode)) )
-  {
+  // Is it the opposite of what we want?
+  if (aNode->IsElement() &&
+      ((aSizeChange == 1 && aNode->AsElement()->IsHTML(nsGkAtoms::small)) ||
+       (aSizeChange == -1 && aNode->AsElement()->IsHTML(nsGkAtoms::big)))) {
     // first populate any nested font tags that have the size attr set
-    res = RelativeFontChangeHelper(aSizeChange, aNode);
-    NS_ENSURE_SUCCESS(res, res);
+    nsresult rv = RelativeFontChangeHelper(aSizeChange, aNode);
+    NS_ENSURE_SUCCESS(rv, rv);
     // in that case, just remove this node and pull up the children
-    res = RemoveContainer(aNode);
-    return res;
+    return RemoveContainer(aNode);
   }
+
   // can it be put inside a "big" or "small"?
-  if (TagCanContain(atom, aNode)) {
+  if (TagCanContain(atom, aNode->AsDOMNode())) {
     // first populate any nested font tags that have the size attr set
-    res = RelativeFontChangeHelper(aSizeChange, aNode);
-    NS_ENSURE_SUCCESS(res, res);
+    nsresult rv = RelativeFontChangeHelper(aSizeChange, aNode);
+    NS_ENSURE_SUCCESS(rv, rv);
+
     // ok, chuck it in.
     // first look at siblings of aNode for matching bigs or smalls.
     // if we find one, move aNode into it.
-    nsCOMPtr<nsIDOMNode> sibling;
-    GetPriorHTMLSibling(aNode, address_of(sibling));
-    if (sibling && nsEditor::NodeIsType(sibling, (aSizeChange==1 ? nsEditProperty::big : nsEditProperty::small)))
-    {
+    nsIContent* sibling = GetPriorHTMLSibling(aNode);
+    if (sibling && sibling->IsHTML(atom)) {
       // previous sib is already right kind of inline node; slide this over into it
-      res = MoveNode(aNode, sibling, -1);
-      return res;
+      return MoveNode(aNode->AsDOMNode(), sibling->AsDOMNode(), -1);
     }
-    sibling = nsnull;
-    GetNextHTMLSibling(aNode, address_of(sibling));
-    if (sibling && nsEditor::NodeIsType(sibling, (aSizeChange==1 ? nsEditProperty::big : nsEditProperty::small)))
-    {
+
+    sibling = GetNextHTMLSibling(aNode);
+    if (sibling && sibling->IsHTML(atom)) {
       // following sib is already right kind of inline node; slide this over into it
-      res = MoveNode(aNode, sibling, 0);
-      return res;
+      return MoveNode(aNode->AsDOMNode(), sibling->AsDOMNode(), 0);
     }
+
     // else insert it above aNode
-    res = InsertContainerAbove(aNode, address_of(tmp), nsAtomString(atom));
-    return res;
+    nsCOMPtr<nsIDOMNode> tmp;
+    return InsertContainerAbove(aNode->AsDOMNode(), address_of(tmp),
+                                nsAtomString(atom));
   }
+
   // none of the above?  then cycle through the children.
   // MOOSE: we should group the children together if possible
   // into a single "big" or "small".  For the moment they are
   // each getting their own.  
-  nsCOMPtr<nsIDOMNodeList> childNodes;
-  res = aNode->GetChildNodes(getter_AddRefs(childNodes));
-  NS_ENSURE_SUCCESS(res, res);
-  if (childNodes)
-  {
-    PRInt32 j;
-    PRUint32 childCount;
-    childNodes->GetLength(&childCount);
-    for (j=childCount-1; j>=0; j--)
-    {
-      nsCOMPtr<nsIDOMNode> childNode;
-      res = childNodes->Item(j, getter_AddRefs(childNode));
-      if ((NS_SUCCEEDED(res)) && (childNode))
-      {
-        res = RelativeFontChangeOnNode(aSizeChange, childNode);
-        NS_ENSURE_SUCCESS(res, res);
-      }
-    }
+  for (nsIContent* child = aNode->GetLastChild();
+       child;
+       child = child->GetPreviousSibling()) {
+    nsresult rv = RelativeFontChangeOnNode(aSizeChange, child);
+    NS_ENSURE_SUCCESS(rv, rv);
   }
-  return res;
+
+  return NS_OK;
 }
 
 NS_IMETHODIMP 
 nsHTMLEditor::GetFontFaceState(bool *aMixed, nsAString &outFace)
 {
   NS_ENSURE_TRUE(aMixed, NS_ERROR_FAILURE);
   *aMixed = true;
   outFace.Truncate();