Fix issue 303 by not shortcutting cons-symbols.

src/mark-compact.cc

 // Copyright 2006-2008 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 165 matching lines @@
   live_old_data_objects_ = 0;
   live_code_objects_ = 0;
   live_map_objects_ = 0;
   live_lo_objects_ = 0;
 #endif
 }
 
 
 void MarkCompactCollector::Finish() {
 #ifdef DEBUG
+  SymbolTable* symbol_table = SymbolTable::cast(Heap::symbol_table());
+  SymbolTableVerifier v;
+  symbol_table->IterateElements(&v);
+
   ASSERT(state_ == SWEEP_SPACES || state_ == REBUILD_RSETS);
   state_ = IDLE;
 #endif
   // The stub cache is not traversed during GC; clear the cache to
   // force lazy re-initialization of it. This must be done after the
   // GC, because it relies on the new address of certain old space
   // objects (empty string, illegal builtin).
   StubCache::Clear();
 }
 
@@ skipping 1584 matching lines @@
 
 void MarkCompactCollector::RebuildRSets() {
 #ifdef DEBUG
   ASSERT(state_ == RELOCATE_OBJECTS);
   state_ = REBUILD_RSETS;
 #endif
   Heap::RebuildRSets();
 }
 
 } }  // namespace v8::internal