Fix idle notification for background tab.

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 15416 matching lines @@
   CHECK_GT(size_with_garbage, initial_size + MB);
   bool finished = false;
   for (int i = 0; i < 200 && !finished; i++) {
     if (i < 10 && CcTest::heap()->incremental_marking()->IsStopped()) {
       CcTest::heap()->StartIdleIncrementalMarking();
     }
     finished = env->GetIsolate()->IdleNotificationDeadline(
         (v8::base::TimeTicks::HighResolutionNow().ToInternalValue() /
          static_cast<double>(v8::base::Time::kMicrosecondsPerSecond)) +
         IdlePauseInSeconds);
+    if (CcTest::heap()->mark_compact_collector()->sweeping_in_progress()) {
+      CcTest::heap()->mark_compact_collector()->EnsureSweepingCompleted();
+    }
   }
   intptr_t final_size = CcTest::heap()->SizeOfObjects();
   CHECK(finished);
   CHECK_LT(final_size, initial_size + 1);
 }
 
 
 TEST(Regress2333) {
   LocalContext env;
   for (int i = 0; i < 3; i++) {
@@ skipping 6480 matching lines @@
 
   v8::TryCatch try_catch(CcTest::isolate());
   timeout_thread.Start();
 
   CompileRun(
       "var ab = new SharedArrayBuffer(4);"
       "var i32a = new Int32Array(ab);"
       "Atomics.futexWait(i32a, 0, 0);");
   CHECK(try_catch.HasTerminated());
 }