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

test/fuzzer/wasm-section-fuzzers.cc

 // 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.
 
 #include "test/fuzzer/wasm-section-fuzzers.h"
 
 #include "include/v8.h"
 #include "src/isolate.h"
 #include "src/wasm/wasm-module-builder.h"
 #include "src/wasm/wasm-module.h"
@@ skipping 39 matching lines @@
     buffer.write(data, size);
   } else {
     buffer.write_u8(section);
     buffer.write_size(size);
     buffer.write(data, size);
   }
 
   ErrorThrower thrower(i_isolate, "decoder");
 
   std::unique_ptr<const WasmModule> module(testing::DecodeWasmModuleForTesting(
-      i_isolate, &zone, &thrower, buffer.begin(), buffer.end(), kWasmOrigin));
+      i_isolate, &thrower, buffer.begin(), buffer.end(), kWasmOrigin));
 
   return 0;
 }