[generators] Create the fixed array holding the registers only once.

src/code-stub-assembler.cc

Index: src/code-stub-assembler.cc
diff --git a/src/code-stub-assembler.cc b/src/code-stub-assembler.cc
index 5fa440ca6dc7295bfa0d07775a811177904cfba3..fe00ddfa8e4a5c2ff6db022254226d92c3740785 100644
--- a/src/code-stub-assembler.cc
+++ b/src/code-stub-assembler.cc
@@ -46,6 +46,10 @@ Node* CodeStubAssembler::UndefinedConstant() {
   return LoadRoot(Heap::kUndefinedValueRootIndex);
 }
 
+Node* CodeStubAssembler::StaleRegisterConstant() {
+  return LoadRoot(Heap::kStaleRegisterRootIndex);
+}
+
 Node* CodeStubAssembler::Float64Round(Node* x) {
   Node* one = Float64Constant(1.0);
   Node* one_half = Float64Constant(0.5);