Make classes and structures in core/layout fast-allocated.

Source/core/layout/OrderIterator.h

Index: Source/core/layout/OrderIterator.h
diff --git a/Source/core/layout/OrderIterator.h b/Source/core/layout/OrderIterator.h
index fadded49dc53902b7faf487f169cee1bcf56f3b4..090a5b590b07de838a90d61cf69bffd8f6c143a6 100644
--- a/Source/core/layout/OrderIterator.h
+++ b/Source/core/layout/OrderIterator.h
@@ -31,6 +31,7 @@
 #ifndef OrderIterator_h
 #define OrderIterator_h
 
+#include "wtf/Allocator.h"
 #include "wtf/Noncopyable.h"
 
 #include <set>
@@ -40,6 +41,7 @@ namespace blink {
 class LayoutBox;
 
 class OrderIterator {
+    DISALLOW_ALLOCATION();
     WTF_MAKE_NONCOPYABLE(OrderIterator);
 public:
     friend class OrderIteratorPopulator;
@@ -63,6 +65,7 @@ private:
 };
 
 class OrderIteratorPopulator {
+    STACK_ALLOCATED();
 public:
     explicit OrderIteratorPopulator(OrderIterator& iterator)
         : m_iterator(iterator)