[wasm] Introduce WasmSharedModuleData and refactor other objects

src/snapshot/code-serializer.cc

Index: src/snapshot/code-serializer.cc
diff --git a/src/snapshot/code-serializer.cc b/src/snapshot/code-serializer.cc
index 511f1117521b257fe4ec02c378d13d1e62c478ec..a51d7a90fc67ccefd89a75816d62d03f7f370525 100644
--- a/src/snapshot/code-serializer.cc
+++ b/src/snapshot/code-serializer.cc
@@ -231,7 +231,7 @@ std::unique_ptr<ScriptData> WasmCompiledModuleSerializer::SerializeWasmModule(
   WasmCompiledModuleSerializer wasm_cs(isolate, 0);
   wasm_cs.reference_map()->AddAttachedReference(*isolate->native_context());
   wasm_cs.reference_map()->AddAttachedReference(
-      *compiled_module->module_bytes());
+      compiled_module->module_bytes());
   ScriptData* data = wasm_cs.Serialize(compiled_module);
   return std::unique_ptr<ScriptData>(data);
 }
@@ -268,10 +268,12 @@ MaybeHandle<FixedArray> WasmCompiledModuleSerializer::DeserializeWasmModule(
 
   MaybeHandle<HeapObject> obj = deserializer.DeserializeObject(isolate);
   if (obj.is_null() || !obj.ToHandleChecked()->IsFixedArray()) return nothing;
-  Handle<WasmCompiledModule> compiled_module =
-      Handle<WasmCompiledModule>::cast(obj.ToHandleChecked());
+  // Cast without type checks, as the module wrapper is not there yet.
+  Handle<WasmCompiledModule> compiled_module(
+      static_cast<WasmCompiledModule*>(*obj.ToHandleChecked()), isolate);
 
   WasmCompiledModule::RecreateModuleWrapper(isolate, compiled_module);
+  DCHECK(WasmCompiledModule::IsWasmCompiledModule(*compiled_module));
   return compiled_module;
 }