Wrap JSFunction bindings in a helper object

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index d6727fab4b1ba1f0645601546bc6331f9b686c3d..c556439f8dc09d2555928cb30ebee1871faa4dab 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -4445,11 +4445,10 @@ Local<v8::Value> Function::GetBoundFunction() const {
   if (!func->shared()->bound()) {
     return v8::Undefined(reinterpret_cast<v8::Isolate*>(func->GetIsolate()));
   }
-  i::Handle<i::FixedArray> bound_args = i::Handle<i::FixedArray>(
-      i::FixedArray::cast(func->function_bindings()));
-  i::Handle<i::Object> original(
-      bound_args->get(i::JSFunction::kBoundFunctionIndex),
-      func->GetIsolate());
+  i::Handle<i::BindingsArray> bound_args = i::Handle<i::BindingsArray>(
+      i::BindingsArray::cast(func->function_bindings()));
+  i::Handle<i::Object> original(bound_args->bound_function(),
+                                func->GetIsolate());
   return Utils::ToLocal(i::Handle<i::JSFunction>::cast(original));
 }