Optimize HandleApiCallHelper and friends

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index e72abc87de14ecf523fe5d892b694287db3cbc26..46c923d01e2d5b3ffddc1c11c3e092a5638af1f4 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -3913,11 +3913,10 @@ Local<Object> v8::Object::FindInstanceInPrototypeChain(
   i::PrototypeIterator iter(isolate, *Utils::OpenHandle(this),
                             i::kStartAtReceiver);
   auto tmpl_info = *Utils::OpenHandle(*tmpl);
-  while (!tmpl_info->IsTemplateFor(iter.GetCurrent())) {
+  while (!tmpl_info->IsTemplateFor(iter.GetCurrent<i::JSObject>())) {
     iter.Advance();
-    if (iter.IsAtEnd()) {
-      return Local<Object>();
-    }
+    if (iter.IsAtEnd()) return Local<Object>();
+    if (!iter.GetCurrent()->IsJSObject()) return Local<Object>();
   }
   // IsTemplateFor() ensures that iter.GetCurrent() can't be a Proxy here.
   return Utils::ToLocal(i::handle(iter.GetCurrent<i::JSObject>(), isolate));
@@ -5810,7 +5809,7 @@ Local<v8::Function> FunctionTemplate::GetFunction() {
 bool FunctionTemplate::HasInstance(v8::Local<v8::Value> value) {
   auto self = Utils::OpenHandle(this);
   auto obj = Utils::OpenHandle(*value);
-  return self->IsTemplateFor(*obj);
+  return obj->IsJSObject() && self->IsTemplateFor(i::JSObject::cast(*obj));
 }