[bootstrapper] extra natives must not use natives syntax.

test/cctest/test-api.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 24151 matching lines @@
 
 
 static void ExtrasBindingTestRuntimeFunction(
     const v8::FunctionCallbackInfo<v8::Value>& args) {
   CHECK_EQ(
       3,
       args[0]->Int32Value(args.GetIsolate()->GetCurrentContext()).FromJust());
   args.GetReturnValue().Set(v8_num(7));
 }
 
+TEST(ExtrasFunctionSource) {
+  v8::Isolate* isolate = CcTest::isolate();
+  v8::HandleScope handle_scope(isolate);
+  LocalContext env;
+
+  v8::Local<v8::Object> binding = env->GetExtrasBindingObject();
+
+  // Functions defined in extras do not expose source code.
+  auto func = binding->Get(env.local(), v8_str("testFunctionToString"))
+                  .ToLocalChecked()
+                  .As<v8::Function>();
+  auto undefined = v8::Undefined(isolate);
+  auto result = func->Call(env.local(), undefined, 0, {})
+                    .ToLocalChecked()
+                    .As<v8::String>();
+  CHECK(result->StrictEquals(v8_str("function foo() { [native code] }")));
+
+  // Functions defined in extras do not show up in the stack trace.
+  auto wrapper = binding->Get(env.local(), v8_str("testStackTrace"))
+                     .ToLocalChecked()
+                     .As<v8::Function>();
+  CHECK(env->Global()->Set(env.local(), v8_str("wrapper"), wrapper).FromJust());
+  ExpectString(
+      "function f(x) { return wrapper(x) }"
+      "function g() { return new Error().stack; }"
+      "f(g)",
+      "Error\n"
+      "    at g (<anonymous>:1:58)\n"
+      "    at f (<anonymous>:1:24)\n"
+      "    at <anonymous>:1:78");
+}
 
 TEST(ExtrasBindingObject) {
   v8::Isolate* isolate = CcTest::isolate();
   v8::HandleScope handle_scope(isolate);
   LocalContext env;
 
   // standalone.gypi ensures we include the test-extra.js file, which should
   // export the tested functions.
   v8::Local<v8::Object> binding = env->GetExtrasBindingObject();
 
@@ skipping 466 matching lines @@
   CHECK(proxy->GetTarget()->SameValue(target));
   CHECK(proxy->GetHandler()->SameValue(handler));
 
   proxy->Revoke();
   CHECK(proxy->IsProxy());
   CHECK(!target->IsProxy());
   CHECK(proxy->IsRevoked());
   CHECK(proxy->GetTarget()->SameValue(target));
   CHECK(proxy->GetHandler()->IsNull());
 }