[api] Make sure InterceptorInfo is always in a verifyable state.

This should fix the Threading1 flakiness that we see on the waterfall.

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/1369993002

Cr-Commit-Position: refs/heads/master@{#30967}

src/api.cc

@@ -1370,13 +1370,13 @@ static void ObjectTemplateSetNamedPropertyHandler(ObjectTemplate* templ,
   EnsureNotInstantiated(cons, "ObjectTemplateSetNamedPropertyHandler");
   auto obj = i::Handle<i::InterceptorInfo>::cast(
       isolate->factory()->NewStruct(i::INTERCEPTOR_INFO_TYPE));
+  obj->set_flags(0);
 
   if (getter != 0) SET_FIELD_WRAPPED(obj, set_getter, getter);
   if (setter != 0) SET_FIELD_WRAPPED(obj, set_setter, setter);
   if (query != 0) SET_FIELD_WRAPPED(obj, set_query, query);
   if (remover != 0) SET_FIELD_WRAPPED(obj, set_deleter, remover);
   if (enumerator != 0) SET_FIELD_WRAPPED(obj, set_enumerator, enumerator);
-  obj->set_flags(0);
   obj->set_can_intercept_symbols(
       !(static_cast<int>(flags) &
         static_cast<int>(PropertyHandlerFlags::kOnlyInterceptStrings)));
@@ -1457,6 +1457,7 @@ void ObjectTemplate::SetHandler(
   EnsureNotInstantiated(cons, "v8::ObjectTemplate::SetHandler");
   auto obj = i::Handle<i::InterceptorInfo>::cast(
       isolate->factory()->NewStruct(i::INTERCEPTOR_INFO_TYPE));
+  obj->set_flags(0);
 
   if (config.getter != 0) SET_FIELD_WRAPPED(obj, set_getter, config.getter);
   if (config.setter != 0) SET_FIELD_WRAPPED(obj, set_setter, config.setter);
@@ -1465,7 +1466,6 @@ void ObjectTemplate::SetHandler(
   if (config.enumerator != 0) {
     SET_FIELD_WRAPPED(obj, set_enumerator, config.enumerator);
   }
-  obj->set_flags(0);
   obj->set_all_can_read(static_cast<int>(config.flags) &
                         static_cast<int>(PropertyHandlerFlags::kAllCanRead));