Add a flag to track detached contexts.

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index 2975d09f63de15cb16e33a0d1c19ba030b5fc976..e78a7be99f4ed80e531a29bb24e82793c118a00e 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -183,7 +183,8 @@ namespace internal {
   V(FixedArray, materialized_objects, MaterializedObjects)                     \
   V(FixedArray, allocation_sites_scratchpad, AllocationSitesScratchpad)        \
   V(FixedArray, microtask_queue, MicrotaskQueue)                               \
-  V(FixedArray, keyed_load_dummy_vector, KeyedLoadDummyVector)
+  V(FixedArray, keyed_load_dummy_vector, KeyedLoadDummyVector)                 \
+  V(FixedArray, detached_contexts, DetachedContexts)
 
 // Entries in this list are limited to Smis and are not visited during GC.
 #define SMI_ROOT_LIST(V)                                                   \