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

Source/core/paint/SVGRootPainter.h

Index: Source/core/paint/SVGRootPainter.h
diff --git a/Source/core/paint/SVGRootPainter.h b/Source/core/paint/SVGRootPainter.h
index f1b5e62e32ef384a520d4542724c4daf61bb8f87..da197d53c2bf41f86fceca2dc6a5953fc8b8aad0 100644
--- a/Source/core/paint/SVGRootPainter.h
+++ b/Source/core/paint/SVGRootPainter.h
@@ -5,6 +5,8 @@
 #ifndef SVGRootPainter_h
 #define SVGRootPainter_h
 
+#include "wtf/Allocator.h"
+
 namespace blink {
 
 struct PaintInfo;
@@ -12,6 +14,7 @@ class LayoutPoint;
 class LayoutSVGRoot;
 
 class SVGRootPainter {
+    STACK_ALLOCATED();
 public:
     SVGRootPainter(LayoutSVGRoot& layoutSVGRoot) : m_layoutSVGRoot(layoutSVGRoot) { }