Allow Turbofan optimization of Ignition generators

src/compiler/js-graph.cc

Index: src/compiler/js-graph.cc
diff --git a/src/compiler/js-graph.cc b/src/compiler/js-graph.cc
index 7def9a82ca65e3835473d81836aa7133840d92d3..229169f792432fbc52a388ca3e48aed7bc18153e 100644
--- a/src/compiler/js-graph.cc
+++ b/src/compiler/js-graph.cc
@@ -48,6 +48,11 @@ Node* JSGraph::OptimizedOutConstant() {
                 HeapConstant(factory()->optimized_out()));
 }
 
+Node* JSGraph::StaleRegisterConstant() {
+  return CACHED(kStaleRegisterConstant,
+                HeapConstant(factory()->stale_register()));
+}
+
 Node* JSGraph::UndefinedConstant() {
   return CACHED(kUndefinedConstant, HeapConstant(factory()->undefined_value()));
 }