Add a weak property type to the virtual machine.

runtime/vm/snapshot.cc

Index: runtime/vm/snapshot.cc
diff --git a/runtime/vm/snapshot.cc b/runtime/vm/snapshot.cc
index 8613340e91493d6e078b4d10ed463cacdc89137f..87bd6eb3ccf5f7f800d9c91bd6e0164802809005 100644
--- a/runtime/vm/snapshot.cc
+++ b/runtime/vm/snapshot.cc
@@ -30,7 +30,7 @@ static bool IsSingletonClassId(intptr_t class_id) {
 static bool IsObjectStoreClassId(intptr_t class_id) {
   // Check if this is a class which is stored in the object store.
   return (class_id == kObjectCid ||
-          (class_id >= kInstanceCid && class_id <= kJSRegExpCid));
+          (class_id >= kInstanceCid && class_id <= kWeakPropertyCid));
 }