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

Source/core/paint/RootInlineBoxPainter.h

Index: Source/core/paint/RootInlineBoxPainter.h
diff --git a/Source/core/paint/RootInlineBoxPainter.h b/Source/core/paint/RootInlineBoxPainter.h
index a398986b69e6f39e1460db28bebb31a37ba5e8b0..29e773c56592c17ee3b6a413d6c1bce4482fb63d 100644
--- a/Source/core/paint/RootInlineBoxPainter.h
+++ b/Source/core/paint/RootInlineBoxPainter.h
@@ -5,6 +5,8 @@
 #ifndef RootInlineBoxPainter_h
 #define RootInlineBoxPainter_h
 
+#include "wtf/Allocator.h"
+
 namespace blink {
 
 struct PaintInfo;
@@ -13,6 +15,7 @@ class LayoutUnit;
 class RootInlineBox;
 
 class RootInlineBoxPainter {
+    STACK_ALLOCATED();
 public:
     RootInlineBoxPainter(RootInlineBox& rootInlineBox) : m_rootInlineBox(rootInlineBox) { }