Don't run the second pass of the pending phantom callbacks if the heap has been torn down.

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index e39912b00d80d87044d98612c4caebabda2c8edc..8cefdeb0a25483440b6b88532bae492b09661185 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -1904,6 +1904,11 @@ void Isolate::Deinit() {
   delete basic_block_profiler_;
   basic_block_profiler_ = NULL;
 
+  for (CancelableTask* task : cancelable_tasks_) {
+    task->Cancel();
+  }
+  cancelable_tasks_.clear();
+
   heap_.TearDown();
   logger_->TearDown();
 
@@ -2783,6 +2788,18 @@ void Isolate::CheckDetachedContextsAfterGC() {
 }
 
 
+void Isolate::RegisterCancelableTask(CancelableTask* task) {
+  cancelable_tasks_.insert(task);
+}
+
+
+void Isolate::RemoveCancelableTask(CancelableTask* task) {
+  auto removed = cancelable_tasks_.erase(task);
+  USE(removed);
+  DCHECK(removed == 1);
+}
+
+
 bool StackLimitCheck::JsHasOverflowed(uintptr_t gap) const {
   StackGuard* stack_guard = isolate_->stack_guard();
 #ifdef USE_SIMULATOR