Add instrumentation to track down Code::CopyFrom crasher.

src/heap.cc

 // Copyright 2012 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 3767 matching lines @@
     maybe_result = lo_space_->AllocateRaw(obj_size, EXECUTABLE);
     if (!maybe_result->To<HeapObject>(&result)) return maybe_result;
   }
 
   // Initialize the object
   result->set_map_no_write_barrier(code_map());
   Code* code = Code::cast(result);
   ASSERT(!isolate_->code_range()->exists() ||
       isolate_->code_range()->contains(code->address()));
   code->set_instruction_size(desc.instr_size);
+  // TODO(mstarzinger): Remove once we found the bug.
+  CHECK(reloc_info->IsByteArray());
   code->set_relocation_info(reloc_info);
+  // TODO(mstarzinger): Remove once we found the bug.
+  CHECK(code->relocation_info()->IsByteArray());
   code->set_flags(flags);
   if (code->is_call_stub() || code->is_keyed_call_stub()) {
     code->set_check_type(RECEIVER_MAP_CHECK);
   }
   code->set_deoptimization_data(empty_fixed_array(), SKIP_WRITE_BARRIER);
   code->InitializeTypeFeedbackInfoNoWriteBarrier(undefined_value());
   code->set_handler_table(empty_fixed_array(), SKIP_WRITE_BARRIER);
   code->set_gc_metadata(Smi::FromInt(0));
   code->set_ic_age(global_ic_age_);
   code->set_prologue_offset(kPrologueOffsetNotSet);
@@ skipping 4011 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   FIXED_ARRAY_SUB_INSTANCE_TYPE_LIST(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   memcpy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   memcpy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 
 } }  // namespace v8::internal