[heap] Do not wait for marking deque uncommit task on tear down.

src/heap/mark-compact.cc

Index: src/heap/mark-compact.cc
diff --git a/src/heap/mark-compact.cc b/src/heap/mark-compact.cc
index d113221edcde594fc51a59c38d43554793b8196b..1a85216e3ff6ce84299081d8bbe3414b6f2a1319 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -2119,7 +2119,6 @@ void MarkingDeque::SetUp() {
 }
 
 void MarkingDeque::TearDown() {
-  CancelOrWaitForUncommitTask();
   delete backing_store_;
 }
 
@@ -2187,26 +2186,13 @@ void MarkingDeque::EnsureCommitted() {
 
 void MarkingDeque::StartUncommitTask() {
   if (!uncommit_task_pending_) {
-    UncommitTask* task = new UncommitTask(heap_->isolate(), this);
-    uncommit_task_id_ = task->id();
     uncommit_task_pending_ = true;
+    UncommitTask* task = new UncommitTask(heap_->isolate(), this);
     V8::GetCurrentPlatform()->CallOnBackgroundThread(
         task, v8::Platform::kShortRunningTask);
   }
 }
 
-void MarkingDeque::CancelOrWaitForUncommitTask() {
-  base::LockGuard<base::Mutex> guard(&mutex_);
-  if (!uncommit_task_pending_ ||
-      heap_->isolate()->cancelable_task_manager()->TryAbort(
-          uncommit_task_id_) != CancelableTaskManager::kTaskRunning) {
-    return;
-  }
-  while (uncommit_task_pending_) {
-    uncommit_task_barrier_.Wait(&mutex_);
-  }
-}
-
 class MarkCompactCollector::ObjectStatsVisitor
     : public MarkCompactCollector::HeapObjectVisitor {
  public: