Delay all exceptions in WebAssembly.instantiate

R=titzer@chromium.org
BUG=v8:5818

Review-Url: https://codereview.chromium.org/2637703004
Cr-Commit-Position: refs/heads/master@{#42372}

src/wasm/wasm-js.cc

@@ -321,32 +321,35 @@ void WebAssemblyInstantiate(const v8::FunctionCallbackInfo<v8::Value>& args) {
   HandleScope scope(isolate);
   ErrorThrower thrower(i_isolate, "WebAssembly.compile()");
 
+  Local<Context> context = isolate->GetCurrentContext();
+  v8::Local<v8::Promise::Resolver> resolver;
+  if (!v8::Promise::Resolver::New(context).ToLocal(&resolver)) return;
+  v8::ReturnValue<v8::Value> return_value = args.GetReturnValue();
+  return_value.Set(resolver->GetPromise());
+
   if (args.Length() < 1) {
     thrower.TypeError("Argument 0 must be a buffer source");
+    resolver->Reject(context, Utils::ToLocal(thrower.Reify()));
     return;
   }
+
   i::MaybeHandle<i::WasmModuleObject> module_obj =
       CreateModuleObject(isolate, args[0], &thrower);
-
-  Local<Context> context = isolate->GetCurrentContext();
-  v8::Local<v8::Promise::Resolver> resolver;
-  if (!v8::Promise::Resolver::New(context).ToLocal(&resolver)) return;
   if (module_obj.is_null()) {
     DCHECK(thrower.error());
     resolver->Reject(context, Utils::ToLocal(thrower.Reify()));
+    return;
+  }
+
+  MaybeLocal<Value> instance = InstantiateModuleImpl(
+      i_isolate, module_obj.ToHandleChecked(), args, &thrower);
+  if (instance.IsEmpty()) {
+    DCHECK(thrower.error());
+    resolver->Reject(context, Utils::ToLocal(thrower.Reify()));
   } else {
-    MaybeLocal<Value> instance = InstantiateModuleImpl(
-        i_isolate, module_obj.ToHandleChecked(), args, &thrower);
-    if (instance.IsEmpty()) {
-      DCHECK(thrower.error());
-      resolver->Reject(context, Utils::ToLocal(thrower.Reify()));
-    } else {
-      DCHECK(!thrower.error());
-      resolver->Resolve(context, instance.ToLocalChecked());
-    }
+    DCHECK(!thrower.error());
+    resolver->Resolve(context, instance.ToLocalChecked());
   }
-  v8::ReturnValue<v8::Value> return_value = args.GetReturnValue();
-  return_value.Set(resolver->GetPromise());
 }
 
 bool GetIntegerProperty(v8::Isolate* isolate, ErrorThrower* thrower,

test/mjsunit/wasm/js-api.js

@@ -587,15 +587,11 @@ assertEq(instantiate.length, 1);
 assertEq(instantiate.name, "instantiate");
 function assertInstantiateError(args, err, msg) {
   var error = null;
-  try {
-    instantiate(...args).catch(e => error = e);
-  } catch(e) {
-    error = e;
-  }
+  instantiate(...args).catch(e => error = e);
   drainJobQueue();
   assertEq(error instanceof err, true);
   assertEq(Boolean(error.stack.match("js-api.js")), true);
-  //TOassertEq(Boolean(error.message.match(msg)), true);
+  //TODO assertEq(Boolean(error.message.match(msg)), true);
 }
 var scratch_memory = new WebAssembly.Memory(new ArrayBuffer(10));
 assertInstantiateError([], TypeError, /requires more than 0 arguments/);