Check for a passed-in type argument vector in the prolog of generic functions.

runtime/vm/intrinsifier.cc

Index: runtime/vm/intrinsifier.cc
diff --git a/runtime/vm/intrinsifier.cc b/runtime/vm/intrinsifier.cc
index 2f641cb324abfcae7e97e46ab7d21c34aba78132..951fd67cf1abe9b873a44995e5aba984a23b43bf 100644
--- a/runtime/vm/intrinsifier.cc
+++ b/runtime/vm/intrinsifier.cc
@@ -32,6 +32,8 @@ bool Intrinsifier::CanIntrinsify(const Function& function) {
     THR_Print("CanIntrinsify %s ->", function.ToQualifiedCString());
   }
   if (!FLAG_intrinsify) return false;
+  // TODO(regis): We do not need to explicitly filter generic functions here,
+  // unless there are errors we don't detect at link time. Revisit if necessary.
   if (function.IsClosureFunction()) {
     if (FLAG_trace_intrinsifier) {
       THR_Print("No, closure function.\n");