If an external string enters the symbol table, make sure to set the...

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 386 matching lines @@
         // the object.
         uint32_t type = map->instance_type();
         bool is_external = (type & kStringRepresentationMask) ==
                            kExternalStringTag;
         if (is_external) {
           bool is_two_byte = (type & kStringEncodingMask) == kTwoByteStringTag;
           byte* resource_addr = reinterpret_cast<byte*>(*p) +
                                 ExternalString::kResourceOffset -
                                 kHeapObjectTag;
           if (is_two_byte) {
-            v8::String::ExternalStringResource* resource =
-                *reinterpret_cast<v8::String::ExternalStringResource**>
+            v8::String::ExternalStringResource** resource =
+                reinterpret_cast<v8::String::ExternalStringResource**>
                 (resource_addr);
-            delete resource;
+            delete *resource;
+            // Clear the resource pointer in the symbol.
+            *resource = NULL;
           } else {
-            v8::String::ExternalAsciiStringResource* resource =
-                *reinterpret_cast<v8::String::ExternalAsciiStringResource**>
+            v8::String::ExternalAsciiStringResource** resource =
+                reinterpret_cast<v8::String::ExternalAsciiStringResource**>
                 (resource_addr);
-            delete resource;
+            delete *resource;
+            // Clear the resource pointer in the symbol.
+            *resource = NULL;
           }
         }
         // Set the entry to null_value (as deleted).
         *p = Heap::null_value();
         pointers_removed_++;
       }
     }
   }
 
   int PointersRemoved() {
@@ skipping 1326 matching lines @@
 
 void MarkCompactCollector::RebuildRSets() {
 #ifdef DEBUG
   ASSERT(state_ == RELOCATE_OBJECTS);
   state_ = REBUILD_RSETS;
 #endif
   Heap::RebuildRSets();
 }
 
 } }  // namespace v8::internal