Bug 188645 - HTMLTableElement.insertRow(-1) should append a new row, per DOM Level 2 HTML

Patch by Ruslan Ismailov <croo@nm.ru>
r=caillon sr=bzbarsky

content/html/content/src/nsHTMLTableElement.cpp

@@ -797,8 +797,9 @@ nsHTMLTableElement::InsertRow(PRInt32 aIndex, nsIDOMHTMLElement** aValue)
       nsCOMPtr<nsIDOMNode> newRowNode(do_QueryInterface(newRow));
       nsCOMPtr<nsIDOMNode> retChild;
 
-      // the index is greater than the number of rows, so just append
-      if ((0 <= aIndex) && (PRInt32(rowCount) <= aIndex)) {
+      // If index is -1 or equal to the number of rows, the new row
+      // is appended.
+      if (aIndex == -1 || PRUint32(aIndex) == rowCount) {
         rv = parent->AppendChild(newRowNode, getter_AddRefs(retChild));
       }
       else