Make assertion scopes thread safe.

src/sweeper-thread.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 38 matching lines @@
        free_list_old_pointer_space_(heap_->paged_space(OLD_POINTER_SPACE)),
        private_free_list_old_data_space_(heap_->paged_space(OLD_DATA_SPACE)),
        private_free_list_old_pointer_space_(
            heap_->paged_space(OLD_POINTER_SPACE)) {
   NoBarrier_Store(&stop_thread_, static_cast<AtomicWord>(false));
 }
 
 
 void SweeperThread::Run() {
   Isolate::SetIsolateThreadLocals(isolate_, NULL);
+  DisallowHeapAllocation no_allocation;
+  DisallowHandleAllocation no_handles;
+  DisallowHandleDereference no_deref;
+
   while (true) {
     start_sweeping_semaphore_->Wait();
 
     if (Acquire_Load(&stop_thread_)) {
       stop_semaphore_->Signal();
       return;
     }
 
     collector_->SweepInParallel(heap_->old_data_space(),
                                 &private_free_list_old_data_space_,
@@ skipping 25 matching lines @@
 
 void SweeperThread::StartSweeping() {
   start_sweeping_semaphore_->Signal();
 }
 
 
 void SweeperThread::WaitForSweeperThread() {
   end_sweeping_semaphore_->Wait();
 }
 } }  // namespace v8::internal