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

Source/core/layout/svg/SVGLayoutSupport.h

Index: Source/core/layout/svg/SVGLayoutSupport.h
diff --git a/Source/core/layout/svg/SVGLayoutSupport.h b/Source/core/layout/svg/SVGLayoutSupport.h
index 1e32aedb23caf961822ff5374af8102e0a6dad9b..ae5ca58c180431653a1fe343480dc2cfa17f2040 100644
--- a/Source/core/layout/svg/SVGLayoutSupport.h
+++ b/Source/core/layout/svg/SVGLayoutSupport.h
@@ -27,6 +27,7 @@
 #include "core/layout/LayoutObject.h"
 #include "core/style/SVGComputedStyleDefs.h"
 #include "platform/graphics/DashArray.h"
+#include "wtf/Allocator.h"
 
 namespace blink {
 
@@ -45,6 +46,7 @@ class StrokeData;
 class TransformState;
 
 class SVGLayoutSupport {
+    STATIC_ONLY(SVGLayoutSupport);
 public:
     // Shares child layouting code between LayoutSVGRoot/LayoutSVG(Hidden)Container
     static void layoutChildren(LayoutObject*, bool selfNeedsLayout);
@@ -111,6 +113,7 @@ private:
 };
 
 class SubtreeContentTransformScope {
+    STACK_ALLOCATED();
 public:
     SubtreeContentTransformScope(const AffineTransform&);
     ~SubtreeContentTransformScope();