[heap] Simplify clearing of normalized map caches.

src/heap/objects-visiting-inl.h

Index: src/heap/objects-visiting-inl.h
diff --git a/src/heap/objects-visiting-inl.h b/src/heap/objects-visiting-inl.h
index 493dce7179c54125f98f614058990679556db2b6..ebf1b919f6394d7d4bd13c114e888c773f5909a1 100644
--- a/src/heap/objects-visiting-inl.h
+++ b/src/heap/objects-visiting-inl.h
@@ -295,6 +295,13 @@ void StaticMarkingVisitor<StaticVisitor>::VisitBytecodeArray(
 template <typename StaticVisitor>
 void StaticMarkingVisitor<StaticVisitor>::VisitNativeContext(
     Map* map, HeapObject* object) {
+  // GC can happen when the context is not fully initialized,
+  // so the cache can be undefined.
+  Object* cache =
+      Context::cast(object)->get(Context::NORMALIZED_MAP_CACHE_INDEX);
+  if (cache->IsNormalizedMapCache()) {
+    NormalizedMapCache::cast(cache)->Clear();
+  }
   FixedBodyVisitor<StaticVisitor, Context::MarkCompactBodyDescriptor,
                    void>::Visit(map, object);
 }