Revert "Revert "Finalize reachable weak persistent handles at isolate shutdown.""

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
diff --git a/runtime/vm/isolate.cc b/runtime/vm/isolate.cc
index 934179687d76401a2fe4d4ebc11843c495cfde19..bd59fb0912a240c3515954ccf6bd5cb740765c51 100644
--- a/runtime/vm/isolate.cc
+++ b/runtime/vm/isolate.cc
@@ -381,6 +381,22 @@ void Isolate::PrintInvokedFunctions() {
 }
 
 
+class FinalizeWeakPersistentHandlesVisitor : public HandleVisitor {
+ public:
+  FinalizeWeakPersistentHandlesVisitor() {
+  }
+
+  void VisitHandle(uword addr) {
+    FinalizablePersistentHandle* handle =
+        reinterpret_cast<FinalizablePersistentHandle*>(addr);
+    FinalizablePersistentHandle::Finalize(handle);
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(FinalizeWeakPersistentHandlesVisitor);
+};
+
+
 void Isolate::Shutdown() {
   ASSERT(this == Isolate::Current());
   ASSERT(top_resource() == NULL);
@@ -402,6 +418,10 @@ void Isolate::Shutdown() {
   delete message_handler();
   set_message_handler(NULL);
 
+  // Finalize any weak persistent handles with a non-null referent.
+  FinalizeWeakPersistentHandlesVisitor visitor;
+  api_state()->weak_persistent_handles().VisitHandles(&visitor);
+
   // Dump all accumalated timer data for the isolate.
   timer_list_.ReportTimers();
   if (FLAG_report_usage_count) {