Fix bogus assert in HeapIterator.

src/spaces.h

 // Copyright 2011 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.
 
 #ifndef V8_SPACES_H_
 #define V8_SPACES_H_
 
 #include "src/allocation.h"
 #include "src/base/atomicops.h"
 #include "src/base/platform/mutex.h"
@@ skipping 460 matching lines @@
   void set_parallel_sweeping(ParallelSweepingState state) {
     base::Release_Store(&parallel_sweeping_, state);
   }
 
   bool TryParallelSweeping() {
     return base::Acquire_CompareAndSwap(
         &parallel_sweeping_, SWEEPING_PENDING, SWEEPING_IN_PROGRESS) ==
             SWEEPING_PENDING;
   }
 
+  bool SweepingCompleted() { return parallel_sweeping() <= SWEEPING_FINALIZE; }
+
   // Manage live byte count (count of bytes known to be live,
   // because they are marked black).
   void ResetLiveBytes() {
     if (FLAG_gc_verbose) {
       PrintF("ResetLiveBytes:%p:%x->0\n",
              static_cast<void*>(this), live_byte_count_);
     }
     live_byte_count_ = 0;
   }
   void IncrementLiveBytes(int by) {
@@ skipping 2534 matching lines @@
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_SPACES_H_