[WIP] do something :-)

Source/core/layout/LayoutBlock.cpp

Index: Source/core/layout/LayoutBlock.cpp
diff --git a/Source/core/layout/LayoutBlock.cpp b/Source/core/layout/LayoutBlock.cpp
index ba5a7b87813f48fd46c34dd56f5a9a42e945c699..b75fac676f8c7a25a56bc653f821e6af4833a8dd 100644
--- a/Source/core/layout/LayoutBlock.cpp
+++ b/Source/core/layout/LayoutBlock.cpp
@@ -70,6 +70,7 @@
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/geometry/FloatQuad.h"
 #include "platform/geometry/TransformState.h"
+#include "wtf/SizeAssertions.h"
 #include "wtf/StdLibExtras.h"
 #include "wtf/TemporaryChange.h"
 
@@ -80,13 +81,7 @@ namespace blink {
 
 using namespace HTMLNames;
 
-struct SameSizeAsLayoutBlock : public LayoutBox {
-    LayoutObjectChildList children;
-    LineBoxList lineBoxes;
-    uint32_t bitfields;
-};
-
-static_assert(sizeof(LayoutBlock) == sizeof(SameSizeAsLayoutBlock), "LayoutBlock should stay small");
+ASSERT_SIZE(LayoutBlock, sizeof(LayoutBox) + 20, sizeof(LayoutBox) + 40);
 
 // This map keeps track of the positioned objects associated with a containing
 // block.