Cleaned up the weak lists hanging off the heap a bit.

src/mark-compact.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 "v8.h"
 
 #include "code-stubs.h"
 #include "compilation-cache.h"
 #include "cpu-profiler.h"
 #include "deoptimizer.h"
@@ skipping 2465 matching lines @@
     }
   }
 
   if (FLAG_track_gc_object_stats) {
     heap()->CheckpointObjectStats();
   }
 }
 
 
 void MarkCompactCollector::ProcessMapCaches() {
-  Object* raw_context = heap()->native_contexts_list_;
+  Object* raw_context = heap()->native_contexts_list();
   while (raw_context != heap()->undefined_value()) {
     Context* context = reinterpret_cast<Context*>(raw_context);
     if (IsMarked(context)) {
       HeapObject* raw_map_cache =
           HeapObject::cast(context->get(Context::MAP_CACHE_INDEX));
       // A map cache may be reachable from the stack. In this case
       // it's already transitively marked and it's too late to clean
       // up its parts.
       if (!IsMarked(raw_map_cache) &&
           raw_map_cache != heap()->undefined_value()) {
@@ skipping 1138 matching lines @@
   HeapObjectIterator js_global_property_cell_iterator(
       heap_->property_cell_space());
   for (HeapObject* cell = js_global_property_cell_iterator.Next();
        cell != NULL;
        cell = js_global_property_cell_iterator.Next()) {
     if (cell->IsPropertyCell()) {
       PropertyCell::BodyDescriptor::IterateBody(cell, &updating_visitor);
     }
   }
 
-  // Update the head of the native contexts list in the heap.
-  updating_visitor.VisitPointer(heap_->native_contexts_list_address());
-
   heap_->string_table()->Iterate(&updating_visitor);
   updating_visitor.VisitPointer(heap_->weak_object_to_code_table_address());
   if (heap_->weak_object_to_code_table()->IsHashTable()) {
     WeakHashTable* table =
         WeakHashTable::cast(heap_->weak_object_to_code_table());
     table->Iterate(&updating_visitor);
     table->Rehash(heap_->isolate()->factory()->undefined_value());
   }
 
   // Update pointers from external string table.
@@ skipping 876 matching lines @@
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 
 
 } }  // namespace v8::internal