Revert of Concurrent sweeping of code space.

src/heap/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_HEAP_SPACES_H_
 #define V8_HEAP_SPACES_H_
 
 #include "src/allocation.h"
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
@@ skipping 996 matching lines @@
     Page* page = Page::FromAddress(addr);
     SkipList* list = page->skip_list();
     if (list == NULL) {
       list = new SkipList();
       page->set_skip_list(list);
     }
 
     list->AddObject(addr, size);
   }
 
-  void Lock() { mutex_.Lock(); }
-
-  void Unlock() { mutex_.Unlock(); }
-
  private:
   static const int kRegionSizeLog2 = 13;
   static const int kRegionSize = 1 << kRegionSizeLog2;
   static const int kSize = Page::kPageSize / kRegionSize;
 
   STATIC_ASSERT(Page::kPageSize % kRegionSize == 0);
 
   Address starts_[kSize];
-  base::Mutex mutex_;
 };
 
 
 // ----------------------------------------------------------------------------
 // A space acquires chunks of memory from the operating system. The memory
 // allocator allocated and deallocates pages for the paged heap spaces and large
 // pages for large object space.
 //
 // Each space has to manage it's own pages.
 //
@@ skipping 1850 matching lines @@
     count = 0;
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_SPACES_H_