[wasm] Use a Managed<WasmModule> to hold metadata about modules.

src/wasm/managed.h

 // Copyright 2016 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.
 
 #ifndef V8_WASM_MANAGED_H_
 #define V8_WASM_MANAGED_H_
 
 #include "src/factory.h"
 #include "src/global-handles.h"
 #include "src/handles.h"
@@ skipping 28 matching lines @@
                                             Handle<Managed<CppType>> handle) {
     Handle<Object> global_handle = isolate->global_handles()->Create(*handle);
     GlobalHandles::MakeWeak(global_handle.location(), global_handle.location(),
                             &Managed<CppType>::Delete,
                             v8::WeakCallbackType::kFinalizer);
   }
   static void Delete(const v8::WeakCallbackInfo<void>& data) {
     Managed<CppType>** p =
         reinterpret_cast<Managed<CppType>**>(data.GetParameter());
     delete (*p)->get();
+    (*p)->set_foreign_address(0);
     GlobalHandles::Destroy(reinterpret_cast<Object**>(p));
   }
 };
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_WASM_MANAGED_H_