Add support for 'order' on grid items

Source/core/rendering/OrderIterator.cpp

Index: Source/core/rendering/OrderIterator.cpp
diff --git a/Source/core/rendering/OrderIterator.cpp b/Source/core/rendering/OrderIterator.cpp
index b11cd58d16af87e72400129b0e18b27d2ebd53a8..141abc60e003b18d590e2a666809697a0d80703e 100644
--- a/Source/core/rendering/OrderIterator.cpp
+++ b/Source/core/rendering/OrderIterator.cpp
@@ -32,11 +32,19 @@
 #include "core/rendering/OrderIterator.h"
 
 #include "core/rendering/RenderFlexibleBox.h"
+#include "core/rendering/RenderGrid.h"
 
 namespace WebCore {
 
 OrderIterator::OrderIterator(const RenderFlexibleBox* flexibleBox)
-    : m_flexibleBox(flexibleBox)
+    : m_containerBox(flexibleBox)
+    , m_currentChild(0)
+    , m_orderValuesIterator(0)
+{
+}
+
+OrderIterator::OrderIterator(const RenderGrid* gridContainerBox)
+    : m_containerBox(gridContainerBox)
     , m_currentChild(0)
     , m_orderValuesIterator(0)
 {
@@ -91,7 +99,7 @@ RenderBox* OrderIterator::next()
                 m_orderValuesIterator = m_orderValues.begin();
             }
 
-            m_currentChild = m_flexibleBox->firstChildBox();
+            m_currentChild = m_containerBox->firstChildBox();
         } else {
             m_currentChild = m_currentChild->nextSiblingBox();
         }