[builtins] migrate C++ String Iterator builtins to baseline TurboFan

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 42a064c823aee39503716702bc1d4c0dd6886adc..3a147c7bca8139f025e9fc0915a7cf0e2a835103 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -1440,9 +1440,17 @@ void Genesis::InitializeGlobal(Handle<JSGlobalObject> global_object,
         factory->NewStringFromAsciiChecked("String Iterator"),
         static_cast<PropertyAttributes>(DONT_ENUM | READ_ONLY));
 
-    InstallFunction(string_iterator_prototype, "next", JS_OBJECT_TYPE,
-                    JSObject::kHeaderSize, MaybeHandle<JSObject>(),
-                    Builtins::kStringIteratorPrototypeNext);
+    Handle<JSFunction> next =
+        InstallFunction(string_iterator_prototype, "next", JS_OBJECT_TYPE,
+                        JSObject::kHeaderSize, MaybeHandle<JSObject>(),
+                        Builtins::kStringIteratorPrototypeNext);
+
+    // Set the expected parameters for %StringIteratorPrototype%.next to 1;
+    // required by builtin.
+    next->shared()->set_internal_formal_parameter_count(0);

[Benedikt Meurer, 2016/09/26 18:38:22]

Comment says 1, but code says 0?

Also why not SimpleInstallFunction(string_iterator_prototype, "next",
Builtins::kStringIteratorPrototypeNext, 0, true) here?

[caitp, 2016/09/27 08:55:56]

AFAIK this intensionally does not include receiver (based on other callers in
this file not including the receiver).

[Benedikt Meurer, 2016/09/27 08:58:54]

Yes, but then the comment should say that it takes 0 parameters (not including
the receiver) :-)

[caitp, 2016/09/27 09:14:18]

Done.

+
+    // Set the length for the function to satisfy ECMA-262.
+    next->shared()->set_length(0);
 
     Handle<JSFunction> string_iterator_function = CreateFunction(
         isolate, factory->NewStringFromAsciiChecked("StringIterator"),