[esnext] prototype runtime implementation for async functions

src/d8.cc

Index: src/d8.cc
diff --git a/src/d8.cc b/src/d8.cc
index 9466ab7d3a727c2fe12d70ac977df0b0cac57f35..c0fc2881ae05eaf19276f22e51b37aa26635dc5e 100644
--- a/src/d8.cc
+++ b/src/d8.cc
@@ -887,6 +887,10 @@ void Shell::Version(const v8::FunctionCallbackInfo<v8::Value>& args) {
                           NewStringType::kNormal).ToLocalChecked());
 }
 
+void Shell::FlushMicrotasks(const v8::FunctionCallbackInfo<v8::Value>& args) {
+  Isolate* isolate = args.GetIsolate();
+  isolate->RunMicrotasks();
+}
 
 void Shell::ReportException(Isolate* isolate, v8::TryCatch* try_catch) {
   HandleScope handle_scope(isolate);
@@ -1204,6 +1208,11 @@ Local<ObjectTemplate> Shell::CreateGlobalTemplate(Isolate* isolate) {
           .ToLocalChecked(),
       os_templ);
 
+  global_template->Set(
+      String::NewFromUtf8(isolate, "flushMicrotasks", NewStringType::kNormal)
+          .ToLocalChecked(),
+      FunctionTemplate::New(isolate, FlushMicrotasks));

[Dan Ehrenberg, 2016/05/04 22:52:36]

I worry that this flushMicrotasks call won't always work so well, as it sort of
violates the microtask model that things don't have to be re-entrant, but I
don't actually have a concrete problem that I can think of here. Existing
Promise tests use an assertLater pattern (found in test/mjsunit/es6/promises.js
for example) and depend on the fact that d8 will not exit until all microtasks
have run. Would that work? Or could you at least guard this behind a special d8
flag so it's not exposed by default?

[caitp (gmail), 2016/05/06 18:45:25]

the assertLater thing is kind of a mess, I would prefer not to rely on a similar
model. It makes tests more complicated, and actually makes it harder to read the
results of the tests when failures occur.

I could put this behind a flag, but I don't believe just exposing it should be a
problem in general.

+
   return global_template;
 }