Finalize reachable weak persistent handles at isolate shutdown.

runtime/vm/dart_api_impl_test.cc

Index: runtime/vm/dart_api_impl_test.cc
diff --git a/runtime/vm/dart_api_impl_test.cc b/runtime/vm/dart_api_impl_test.cc
index 0f1435746fc262fcc50fede506346957fbf5def6..632f4a4f71dc45ff5c4d9e8ec206b405ef29246b 100644
--- a/runtime/vm/dart_api_impl_test.cc
+++ b/runtime/vm/dart_api_impl_test.cc
@@ -1438,6 +1438,19 @@ TEST_CASE(WeakPersistentHandleCallback) {
 }
 
 
+UNIT_TEST_CASE(WeakPersistentHandlesCallbackShutdown) {
+  TestCase::CreateTestIsolate();
+  Dart_EnterScope();
+  Dart_Handle ref = Dart_True();
+  int peer = 1234;
+  Dart_NewWeakPersistentHandle(ref,
+                               &peer,
+                               WeakPersistentHandlePeerFinalizer);
+  Dart_ShutdownIsolate();
+  EXPECT(peer == 42);
+}
+
+
 TEST_CASE(ObjectGroups) {
   Dart_Handle strong = Dart_Null();
   EXPECT(Dart_IsNull(strong));