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

Source/core/paint/FieldsetPainter.h

Index: Source/core/paint/FieldsetPainter.h
diff --git a/Source/core/paint/FieldsetPainter.h b/Source/core/paint/FieldsetPainter.h
index 35ae86af65979421a1ba4fb09ca7d1b2bbd6bdb6..a6955f19674d27e82fc35cc000a1b086f783305d 100644
--- a/Source/core/paint/FieldsetPainter.h
+++ b/Source/core/paint/FieldsetPainter.h
@@ -5,6 +5,8 @@
 #ifndef FieldsetPainter_h
 #define FieldsetPainter_h
 
+#include "wtf/Allocator.h"
+
 namespace blink {
 
 struct PaintInfo;
@@ -12,6 +14,7 @@ class LayoutPoint;
 class LayoutFieldset;
 
 class FieldsetPainter {
+    STACK_ALLOCATED();
 public:
     FieldsetPainter(LayoutFieldset& layoutFieldset) : m_layoutFieldset(layoutFieldset) { }