[serializer] small fixes for blink snapshot.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index d3a180cee9d5a478797a72198bd81f3f75fbac28..d65896fab1bfa4d19290f10bdf4118b104efb35d 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -1239,7 +1239,6 @@ Local<FunctionTemplate> FunctionTemplate::NewWithFastHandler(
     experimental::FastAccessorBuilder* fast_handler, v8::Local<Value> data,
     v8::Local<Signature> signature, int length) {
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
-  DCHECK(!i_isolate->serializer_enabled());
   LOG_API(i_isolate, FunctionTemplate, NewWithFastHandler);
   ENTER_V8(i_isolate);
   return FunctionTemplateNew(i_isolate, callback, fast_handler, data, signature,
@@ -1250,7 +1249,6 @@ Local<FunctionTemplate> FunctionTemplate::NewWithCache(
     Isolate* isolate, FunctionCallback callback, Local<Private> cache_property,
     Local<Value> data, Local<Signature> signature, int length) {
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
-  DCHECK(!i_isolate->serializer_enabled());

[vogelheim, 2016/11/09 12:19:24]

Ah. I'm rather certain this DCHECK is a copy of the one in #1242, since the
..WithCache logic was patterned after ..WithFastHandler. I'm not quite sure why
that one is there; but I agree they can probably both be removed. :-)

   LOG_API(i_isolate, FunctionTemplate, NewWithFastHandler);
   ENTER_V8(i_isolate);
   return FunctionTemplateNew(i_isolate, callback, nullptr, data, signature,