[turbofan] Handle void returns in instruction selector.

test/cctest/compiler/test-run-machops.cc

Index: test/cctest/compiler/test-run-machops.cc
diff --git a/test/cctest/compiler/test-run-machops.cc b/test/cctest/compiler/test-run-machops.cc
index b1fc36968fb7ac48497b5e00893a3cb17da448a7..10e9e9f0edaa1e91a36b02273807a177757cc8b2 100644
--- a/test/cctest/compiler/test-run-machops.cc
+++ b/test/cctest/compiler/test-run-machops.cc
@@ -82,6 +82,13 @@ TEST(CodeGenInt32Binop) {
 }
 
 
+TEST(CodeGenNop) {
+  RawMachineAssemblerTester<void> m;
+  m.Return(m.Int32Constant(0));
+  m.GenerateCode();
+}
+
+
 #if V8_TURBOFAN_BACKEND_64
 static Node* Int64Input(RawMachineAssemblerTester<int64_t>* m, int index) {
   switch (index) {