Remove support for specifying the number of available threads

src/heap/heap.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 "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/bits.h"
 #include "src/base/once.h"
@@ skipping 5252 matching lines @@
   // call Heap::TearDown() to release allocated memory.
   //
   // If the heap is not yet configured (e.g. through the API), configure it.
   // Configuration is based on the flags new-space-size (really the semispace
   // size) and old-space-size if set or the initial values of semispace_size_
   // and old_generation_size_ otherwise.
   if (!configured_) {
     if (!ConfigureHeapDefault()) return false;
   }
 
-  concurrent_sweeping_enabled_ =
-      FLAG_concurrent_sweeping && isolate_->max_available_threads() > 1;
+  concurrent_sweeping_enabled_ = FLAG_concurrent_sweeping;
 
   base::CallOnce(&initialize_gc_once, &InitializeGCOnce);
 
   MarkMapPointersAsEncoded(false);
 
   // Set up memory allocator.
   if (!isolate_->memory_allocator()->SetUp(MaxReserved(), MaxExecutableSize()))
     return false;
 
   // Set up new space.
@@ skipping 1025 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 }
 }  // namespace v8::internal