Let the second pass phantom callbacks run in a separate task on the foreground thread.

test/cctest/test-api.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3257 matching lines @@
 TEST(TwoPassPhantomCallbacks) {
   auto isolate = CcTest::isolate();
   const size_t kLength = 20;
   int instance_counter = 0;
   for (size_t i = 0; i < kLength; ++i) {
     auto data = new TwoPassCallbackData(isolate, &instance_counter);
     data->SetWeak();
   }
   CHECK_EQ(static_cast<int>(kLength), instance_counter);
   CcTest::heap()->CollectAllGarbage();
+  EmptyMessageQueues(isolate);
   CHECK_EQ(0, instance_counter);
 }
 
 
 TEST(TwoPassPhantomCallbacksNestedGc) {
   auto isolate = CcTest::isolate();
   const size_t kLength = 20;
   TwoPassCallbackData* array[kLength];
   int instance_counter = 0;
   for (size_t i = 0; i < kLength; ++i) {
     array[i] = new TwoPassCallbackData(isolate, &instance_counter);
     array[i]->SetWeak();
   }
   array[5]->MarkTriggerGc();
   array[10]->MarkTriggerGc();
   array[15]->MarkTriggerGc();
   CHECK_EQ(static_cast<int>(kLength), instance_counter);
   CcTest::heap()->CollectAllGarbage();
+  EmptyMessageQueues(isolate);
   CHECK_EQ(0, instance_counter);
 }
 
 
 namespace {
 
 void* IntKeyToVoidPointer(int key) { return reinterpret_cast<void*>(key << 1); }
 
 
 Local<v8::Object> NewObjectForIntKey(
@@ skipping 29 matching lines @@
   }
   static K KeyFromWeakCallbackInfo(
       const v8::WeakCallbackInfo<WeakCallbackDataType>& data) {
     return data.GetParameter()->key;
   }
   static void DisposeCallbackData(WeakCallbackDataType* data) { delete data; }
   static void Dispose(v8::Isolate* isolate, v8::Global<V> value, K key) {
     CHECK_EQ(IntKeyToVoidPointer(key),
              v8::Object::GetAlignedPointerFromInternalField(value, 0));
   }
+  static void OnWeakCallback(
+      const v8::WeakCallbackInfo<WeakCallbackDataType>&) {}
   static void DisposeWeak(
       const v8::WeakCallbackInfo<WeakCallbackDataType>& info) {
     K key = KeyFromWeakCallbackInfo(info);
     CHECK_EQ(IntKeyToVoidPointer(key), info.GetInternalField(0));
     DisposeCallbackData(info.GetParameter());
   }
 };
 
 
 template <typename Map>
@@ skipping 3444 matching lines @@
       FlagAndPersistent object;
       {
         v8::HandleScope handle_scope(isolate);
         object.handle.Reset(isolate, v8::Object::New(isolate));
       }
       object.flag = false;
       object.handle.SetWeak(&object, gc_forcing_callback[inner_gc],
                             v8::WeakCallbackType::kParameter);
       object.handle.MarkIndependent();
       invoke_gc[outer_gc]();
+      EmptyMessageQueues(isolate);
       CHECK(object.flag);
     }
   }
 }
 
 
 v8::Handle<Function> args_fun;
 
 
 static void ArgumentsTestCallback(
@@ skipping 5059 matching lines @@
     v8::HandleScope scope(isolate);
     handle3.Reset(isolate, v8::Object::New(isolate));
     handle2.Reset(isolate, v8::Object::New(isolate));
     handle1.Reset(isolate, v8::Object::New(isolate));
   }
   handle2.SetWeak(&handle2, DisposingCallback,
                   v8::WeakCallbackType::kParameter);
   handle3.SetWeak(&handle3, HandleCreatingCallback1,
                   v8::WeakCallbackType::kParameter);
   CcTest::heap()->CollectAllGarbage();
+  EmptyMessageQueues(isolate);
 }
 
 
 THREADED_TEST(CheckForCrossContextObjectLiterals) {
   v8::V8::Initialize();
 
   const int nof = 2;
   const char* sources[nof] = {
     "try { [ 2, 3, 4 ].forEach(5); } catch(e) { e.toString(); }",
     "Object()"
@@ skipping 9951 matching lines @@
       "    fake.age;\n"
       "    result = 1;\n"
       "  } catch (e) {\n"
       "  }\n"
       "  test(d+1);\n"
       "}\n"
       "test(0);\n"
       "result;\n",
       0);
 }