IntersectionObserver: second cut.

third_party/WebKit/Source/core/dom/ElementRareData.cpp

Index: third_party/WebKit/Source/core/dom/ElementRareData.cpp
diff --git a/third_party/WebKit/Source/core/dom/ElementRareData.cpp b/third_party/WebKit/Source/core/dom/ElementRareData.cpp
index edd8ba49ea8b1c9ec448c0b24d0993b3ef4cbc1e..66cdf1050c8b250c77a36af8d2da4f79d77a5ad6 100644
--- a/third_party/WebKit/Source/core/dom/ElementRareData.cpp
+++ b/third_party/WebKit/Source/core/dom/ElementRareData.cpp
@@ -28,9 +28,21 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+/* STATIC_ASSERT_STRUCT_SIZES_EQUAL
+
+   Compile-time assert that a struct has the expected size.  The old way to do this is:
+
+   static_assert(sizeof(StructWithSameSize) == sizeof(Struct)), "Wrong size!");
+
+   However, static_assert will not emit the actual sizes of the structs in question, and
+   there is no way to use an interpolated string in the error message.  By contrast,
+   STATIC_ASSERT_STRUCT_SIZES_EQUAL will ensure that the actual sizes of the compared structs
+   will appear in the compiler error output.
+*/
+
 #include "config.h"
 #include "core/dom/ElementRareData.h"
-
+#include "core/dom/IntersectionObservation.h"
 #include "core/style/ComputedStyle.h"
 
 namespace blink {
@@ -40,8 +52,8 @@ struct SameSizeAsElementRareData : NodeRareData {
     LayoutSize sizeForResizing;
     IntSize scrollOffset;
     void* pointer;
-    RawPtrWillBeMember<void*> willbeMember[11];
-    PersistentWillBeMember<void*> persistent[1];
+    RawPtrWillBeMember<void*> willbeMember[12];
+    PersistentWillBeMember<void*> persistent[3];
 };
 
 CSSStyleDeclaration& ElementRareData::ensureInlineCSSStyleDeclaration(Element* ownerElement)
@@ -69,11 +81,14 @@ DEFINE_TRACE_AFTER_DISPATCH(ElementRareData)
 #endif
     visitor->trace(m_elementAnimations);
     visitor->trace(m_cssomWrapper);
+    visitor->trace(m_weakPointerFactory);
     visitor->trace(m_customElementDefinition);
     visitor->trace(m_generatedBefore);
     visitor->trace(m_generatedAfter);
     visitor->trace(m_generatedFirstLetter);
     visitor->trace(m_backdrop);
+    visitor->trace(m_intersectionObservers);
+    visitor->trace(m_intersectionObservations);
     NodeRareData::traceAfterDispatch(visitor);
 }