Bug 1569315 - Sink prototype fetching into AllocNewFunction r=tcampbell

GetFunctionPrototype already returns null for 'normal' functions. Eventually
the real %FunctionPrototype% is provided based on the class proto key.

Differential Revision: https://phabricator.services.mozilla.com/D39770

js/src/frontend/BinASTParserPerTokenizer.cpp

@@ -263,7 +263,7 @@ JS::Result<FunctionBox*> BinASTParserPerTokenizer<Tok>::buildFunctionBox(
   RootedFunction fun(cx_);
   BINJS_TRY_VAR(fun, !pc_ ? lazyScript_->functionNonDelazifying()
                           : AllocNewFunction(cx_, atom, syntax, generatorKind,
-                                             functionAsyncKind, nullptr));
+                                             functionAsyncKind));
   MOZ_ASSERT_IF(pc_, fun->explicitName() == atom);
 
   mozilla::Maybe<Directives> directives;