Integrate concurrent sweeping with incremental marking.

src/heap.h

 // 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 1679 matching lines @@
            old_pointer_space()->IsLazySweepingComplete();
   }
 
   bool AdvanceSweepers(int step_size) {
     ASSERT(!FLAG_parallel_sweeping && !FLAG_concurrent_sweeping);
     bool sweeping_complete = old_data_space()->AdvanceSweeper(step_size);
     sweeping_complete &= old_pointer_space()->AdvanceSweeper(step_size);
     return sweeping_complete;
   }
 
+  bool EnsureSweepersProgressed(int step_size) {
+    bool sweeping_complete = old_data_space()->EnsureSweeperProgress(step_size);
+    sweeping_complete &= old_pointer_space()->EnsureSweeperProgress(step_size);
+    return sweeping_complete;
+  }
+
   ExternalStringTable* external_string_table() {
     return &external_string_table_;
   }
 
   ErrorObjectList* error_object_list() {
     return &error_object_list_;
   }
 
   // Returns the current sweep generation.
   int sweep_generation() {
@@ skipping 1285 matching lines @@
   AssertNoAllocation no_alloc;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_