[runtime] Port simple String.prototype.indexOf cases to TF Builtin

src/builtins/builtins-utils.h

Index: src/builtins/builtins-utils.h
diff --git a/src/builtins/builtins-utils.h b/src/builtins/builtins-utils.h
index 80e0d29f17ec42303a0ef0c7185546be09d17b4f..05d41cfeb385d281e8e4db97f834bcbabe360ca1 100644
--- a/src/builtins/builtins-utils.h
+++ b/src/builtins/builtins-utils.h
@@ -27,7 +27,7 @@ class BuiltinArguments : public Arguments {
     return Arguments::operator[](index);
   }
 
-  template <class S>
+  template <class S = Object>
   Handle<S> at(int index) {
     DCHECK_LT(index, length());
     return Arguments::at<S>(index);