Preserve optimized code map during GCs weakly.

test/cctest/test-heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
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 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
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 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
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@@ skipping 2796 matching lines @@
   i::FLAG_flush_code_incrementally = true;
 
   // Experimental natives are compiled during snapshot deserialization.
   // This test breaks because heap layout changes in a way that closure
   // is visited before shared function info.
   i::FLAG_harmony_typed_arrays = false;
   i::FLAG_harmony_array_buffer = false;
 
   CcTest::InitializeVM();
   Isolate* isolate = Isolate::Current();
-  // Force experimental natives to compile to normalize heap layout.
   Heap* heap = isolate->heap();
   HandleScope scope(isolate);
 
   // Perform one initial GC to enable code flushing.
   heap->CollectAllGarbage(Heap::kAbortIncrementalMarkingMask);
 
   // Prepare a shared function info eligible for code flushing for which
   // the unoptimized code will be replaced during optimization.
   Handle<SharedFunctionInfo> shared1;
   {
@@ skipping 269 matching lines @@
   }
   // An entire block of handles has been filled.
   // Next handle would require a new block.
   ASSERT(data->next == data->limit);
 
   DeferredHandleScope deferred(isolate);
   DummyVisitor visitor;
   isolate->handle_scope_implementer()->Iterate(&visitor);
   deferred.Detach();
 }