[wasm] Update WasmMemoryObject correctly when module memory is exported.

src/wasm/wasm-module.cc

 // Copyright 2015 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 <memory>
 
 #include "src/base/atomic-utils.h"
 #include "src/code-stubs.h"
 
 #include "src/macro-assembler.h"
@@ skipping 1776 matching lines @@
         case kExternalMemory: {
           // Export the memory as a WebAssembly.Memory object.
           Handle<WasmMemoryObject> memory_object;
           if (!instance->has_memory_object()) {
             // If there was no imported WebAssembly.Memory object, create one.
             Handle<JSArrayBuffer> buffer(instance->get_memory_buffer(),
                                          isolate_);
             memory_object = WasmMemoryObject::New(
                 isolate_, buffer,
                 (module_->max_mem_pages != 0) ? module_->max_mem_pages : -1);
-            instance->set_memory_object(*memory_object);
           } else {
             memory_object = Handle<WasmMemoryObject>(
                 instance->get_memory_object(), isolate_);
             DCHECK(WasmJs::IsWasmMemoryObject(isolate_, memory_object));
             memory_object->ResetInstancesLink(isolate_);
           }
 
           desc.set_value(memory_object);
           break;
         }
@@ skipping 549 matching lines @@
 MaybeHandle<String> WasmCompiledModule::GetFunctionName(
     Handle<WasmCompiledModule> compiled_module, uint32_t func_index) {
   DCHECK_LT(func_index, compiled_module->module()->functions.size());
   WasmFunction& function = compiled_module->module()->functions[func_index];
   Isolate* isolate = compiled_module->GetIsolate();
   MaybeHandle<String> string = ExtractStringFromModuleBytes(
       isolate, compiled_module, function.name_offset, function.name_length);
   if (!string.is_null()) return string.ToHandleChecked();
   return {};
 }