Expose v8::Function::IsBuiltin to public API.

test/cctest/test-api.cc

Index: test/cctest/test-api.cc
diff --git a/test/cctest/test-api.cc b/test/cctest/test-api.cc
index 6e955bd9787b7e4f58149dbadb72cd02c1f0aebd..38ca9f59adf0c5480578368f89c406b486282244 100644
--- a/test/cctest/test-api.cc
+++ b/test/cctest/test-api.cc
@@ -17537,6 +17537,23 @@ THREADED_TEST(ScriptColumnNumber) {
 }
 
 
+THREADED_TEST(FunctionIsBuiltin) {
+  LocalContext env;
+  v8::HandleScope scope(env->GetIsolate());
+  v8::Local<v8::Function> f;
+  f = v8::Local<v8::Function>::Cast(CompileRun("Math.floor"));
+  CHECK(f->IsBuiltin());
+  f = v8::Local<v8::Function>::Cast(CompileRun("Object"));
+  CHECK(f->IsBuiltin());
+  f = v8::Local<v8::Function>::Cast(CompileRun("Object.__defineSetter__"));
+  CHECK(f->IsBuiltin());
+  f = v8::Local<v8::Function>::Cast(CompileRun("Array.prototype.toString"));
+  CHECK(f->IsBuiltin());
+  f = v8::Local<v8::Function>::Cast(CompileRun("function a() {}; a;"));
+  CHECK(!f->IsBuiltin());
+}
+
+
 THREADED_TEST(FunctionGetScriptId) {
   LocalContext env;
   v8::HandleScope scope(env->GetIsolate());