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

src/wasm/wasm-js.cc

Index: src/wasm/wasm-js.cc
diff --git a/src/wasm/wasm-js.cc b/src/wasm/wasm-js.cc
index 36f286f73cffcd58a940d74e7d06442ed8fe1f92..c4de120863831e61e325bc6ba736fd94122e47f5 100644
--- a/src/wasm/wasm-js.cc
+++ b/src/wasm/wasm-js.cc
@@ -92,10 +92,8 @@ void VerifyModule(const v8::FunctionCallbackInfo<v8::Value>& args) {
   RawBuffer buffer = GetRawBufferSource(args[0], &thrower);
   if (thrower.error()) return;
 
-  i::Zone zone(isolate->allocator());
-  internal::wasm::ModuleResult result =
-      internal::wasm::DecodeWasmModule(isolate, &zone, buffer.start, buffer.end,
-                                       true, internal::wasm::kWasmOrigin);
+  internal::wasm::ModuleResult result = internal::wasm::DecodeWasmModule(
+      isolate, buffer.start, buffer.end, true, internal::wasm::kWasmOrigin);
 
   if (result.failed()) {
     thrower.Failed("", result);