Add map transition for observed objects

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 470d8e89aedf2dcb26fdf92ab1cfbd019925a3cb..98ce4ba4bdc75eda0995f3de08c105d4653ca452 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -5483,7 +5483,7 @@ class Map: public HeapObject {
   MUST_USE_RESULT MaybeObject* AsElementsKind(ElementsKind kind);
   MUST_USE_RESULT MaybeObject* CopyAsElementsKind(ElementsKind kind,
                                                   TransitionFlag flag);
-
+  MUST_USE_RESULT MaybeObject* CopyForObserved();
   MUST_USE_RESULT MaybeObject* CopyNormalized(PropertyNormalizationMode mode,
                                               NormalizedMapSharingMode sharing);