Oilpan: Add a checkHeader ASSERT to HeapObjectHeader::fromPayload

Source/platform/heap/Heap.h

Index: Source/platform/heap/Heap.h
diff --git a/Source/platform/heap/Heap.h b/Source/platform/heap/Heap.h
index 239139434f5a54ca4023c309674c5c0dd6bf2e3b..1f1101d6dbdb6277daa1302ad5a0428e39a6d91c 100644
--- a/Source/platform/heap/Heap.h
+++ b/Source/platform/heap/Heap.h
@@ -243,13 +243,6 @@ private:
 #endif
 };
 
-inline HeapObjectHeader* HeapObjectHeader::fromPayload(const void* payload)
-{
-    Address addr = reinterpret_cast<Address>(const_cast<void*>(payload));
-    HeapObjectHeader* header = reinterpret_cast<HeapObjectHeader*>(addr - sizeof(HeapObjectHeader));
-    return header;
-}
-
 class FreeListEntry final : public HeapObjectHeader {
 public:
     NO_SANITIZE_ADDRESS
@@ -1189,6 +1182,14 @@ size_t HeapObjectHeader::payloadSize()
     return size - sizeof(HeapObjectHeader);
 }
 
+inline HeapObjectHeader* HeapObjectHeader::fromPayload(const void* payload)
+{
+    Address addr = reinterpret_cast<Address>(const_cast<void*>(payload));
+    HeapObjectHeader* header = reinterpret_cast<HeapObjectHeader*>(addr - sizeof(HeapObjectHeader));
+    header->checkHeader();
+    return header;
+}
+
 NO_SANITIZE_ADDRESS inline
 bool HeapObjectHeader::isMarked() const
 {