Adding V8_WARN_UNUSED_RESULT for specified TODOs

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/assembler-inl.h"
 #include "src/base/adapters.h"
 #include "src/base/atomic-utils.h"
 #include "src/code-stubs.h"
@@ skipping 2665 matching lines @@
   return helper.Build();
 }
 
 namespace {
 
 void RejectPromise(Isolate* isolate, ErrorThrower* thrower,
                    Handle<JSPromise> promise) {
   v8::Local<v8::Promise::Resolver> resolver =
       v8::Utils::PromiseToLocal(promise).As<v8::Promise::Resolver>();
   Handle<Context> context(isolate->context(), isolate);
-  resolver->Reject(v8::Utils::ToLocal(context),
+  auto maybe = resolver->Reject(v8::Utils::ToLocal(context),
                    v8::Utils::ToLocal(thrower->Reify()));
+  CHECK(!maybe.IsNothing());
 }
 
 void ResolvePromise(Isolate* isolate, Handle<JSPromise> promise,
                     Handle<Object> result) {
   v8::Local<v8::Promise::Resolver> resolver =
       v8::Utils::PromiseToLocal(promise).As<v8::Promise::Resolver>();
   Handle<Context> context(isolate->context(), isolate);
-  resolver->Resolve(v8::Utils::ToLocal(context), v8::Utils::ToLocal(result));
+  auto maybe = resolver->Resolve(v8::Utils::ToLocal(context),
+                                 v8::Utils::ToLocal(result));
+  CHECK(!maybe.IsNothing());
 }
 
 }  // namespace
 
 void wasm::AsyncCompile(Isolate* isolate, Handle<JSPromise> promise,
                         const ModuleWireBytes& bytes) {
   ErrorThrower thrower(isolate, nullptr);
   MaybeHandle<WasmModuleObject> module_object =
       SyncCompile(isolate, &thrower, bytes);
   if (thrower.error()) {
@@ skipping 46 matching lines @@
   Handle<String> module_property_name =
       isolate->factory()->InternalizeUtf8String("module");
   Handle<String> instance_property_name =
       isolate->factory()->InternalizeUtf8String("instance");
   JSObject::AddProperty(ret, module_property_name, module, NONE);
   JSObject::AddProperty(ret, instance_property_name,
                         instance_object.ToHandleChecked(), NONE);
 
   ResolvePromise(isolate, promise, ret);
 }