[turbofan] Ensure that NTLs are always properly connected to the end.

test/unittests/compiler/graph-unittest.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "test/unittests/compiler/graph-unittest.h"
 
 #include "src/compiler/node-properties-inl.h"
 #include "test/unittests/compiler/node-test-utils.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 GraphTest::GraphTest(int num_parameters) : common_(zone()), graph_(zone()) {
   graph()->SetStart(graph()->NewNode(common()->Start(num_parameters)));
+  graph()->SetEnd(graph()->NewNode(common()->End(), graph()->start()));
 }
 
 
 GraphTest::~GraphTest() {}
 
 
 Node* GraphTest::Parameter(int32_t index) {
   return graph()->NewNode(common()->Parameter(index), graph()->start());
 }
 
@@ skipping 59 matching lines @@
       Unique<HeapObject>::CreateImmovable(factory()->false_value()));
 }
 
 
 Matcher<Node*> GraphTest::IsTrueConstant() {
   return IsHeapConstant(
       Unique<HeapObject>::CreateImmovable(factory()->true_value()));
 }
 
 
+Matcher<Node*> GraphTest::IsUndefinedConstant() {
+  return IsHeapConstant(
+      Unique<HeapObject>::CreateImmovable(factory()->undefined_value()));
+}
+
+
 TypedGraphTest::TypedGraphTest(int num_parameters)
     : GraphTest(num_parameters),
       typer_(isolate(), graph(), MaybeHandle<Context>()) {}
 
 
 TypedGraphTest::~TypedGraphTest() {}
 
 
 Node* TypedGraphTest::Parameter(Type* type, int32_t index) {
   Node* node = GraphTest::Parameter(index);
@@ skipping 17 matching lines @@
   EXPECT_LT(0, n0->id());
   EXPECT_LT(0, n1->id());
   EXPECT_NE(n0->id(), n1->id());
   EXPECT_EQ(&kDummyOperator, n0->op());
   EXPECT_EQ(&kDummyOperator, n1->op());
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8