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

Source/core/paint/GridPainter.h

Index: Source/core/paint/GridPainter.h
diff --git a/Source/core/paint/GridPainter.h b/Source/core/paint/GridPainter.h
index 9c33efb6e4e0e11b6fdeb67d91c81e0cc24e9b0b..3b0648d5f235ff1893dbcbd34d83ca24b1b8d950 100644
--- a/Source/core/paint/GridPainter.h
+++ b/Source/core/paint/GridPainter.h
@@ -5,6 +5,8 @@
 #ifndef GridPainter_h
 #define GridPainter_h
 
+#include "wtf/Allocator.h"
+
 namespace blink {
 
 struct PaintInfo;
@@ -13,6 +15,7 @@ class LayoutBox;
 class LayoutGrid;
 
 class GridPainter {
+    STACK_ALLOCATED();
 public:
     GridPainter(LayoutGrid& layoutGrid) : m_layoutGrid(layoutGrid) { }