Remove sequential sweeping mode and perform lazy sweeping when no sweeper threads are active.

src/isolate.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stdlib.h>
 
 #include "src/v8.h"
 
 #include "src/ast.h"
 #include "src/base/platform/platform.h"
@@ skipping 1541 matching lines @@
 
     for (int i = 0; i < num_sweeper_threads_; i++) {
       sweeper_thread_[i]->Stop();
       delete sweeper_thread_[i];
       sweeper_thread_[i] = NULL;
     }
     delete[] sweeper_thread_;
     sweeper_thread_ = NULL;
 
     if (FLAG_job_based_sweeping &&
-        heap_.mark_compact_collector()->IsConcurrentSweepingInProgress()) {
-      heap_.mark_compact_collector()->WaitUntilSweepingCompleted();
+        heap_.mark_compact_collector()->sweeping_in_progress()) {
+      heap_.mark_compact_collector()->EnsureSweepingCompleted();
     }
 
     if (FLAG_hydrogen_stats) GetHStatistics()->Print();
 
     if (FLAG_print_deopt_stress) {
       PrintF(stdout, "=== Stress deopt counter: %u\n", stress_deopt_count_);
     }
 
     // We must stop the logger before we tear down other components.
     Sampler* sampler = logger_->sampler();
@@ skipping 775 matching lines @@
   if (prev_ && prev_->Intercept(flag)) return true;
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 } }  // namespace v8::internal