Allow Turbofan optimization of Ignition generators

src/types.cc

Index: src/types.cc
diff --git a/src/types.cc b/src/types.cc
index eed80db8205aabf8f74339871b5292fffbb480bb..c2228610b5d3f459e895ec01fba8b1c8bbebd017 100644
--- a/src/types.cc
+++ b/src/types.cc
@@ -192,7 +192,8 @@ Type::bitset BitsetType::Lub(i::Map* map) {
              map == heap->no_interceptor_result_sentinel_map() ||
              map == heap->termination_exception_map() ||
              map == heap->arguments_marker_map() ||
-             map == heap->optimized_out_map());
+             map == heap->optimized_out_map() ||
+             map == heap->stale_register_map());
       return kInternal & kTaggedPointer;
     }
     case HEAP_NUMBER_TYPE: