[turbofan] Connect loops to end via Terminate during graph building.

test/cctest/compiler/test-control-reducer.cc

Index: test/cctest/compiler/test-control-reducer.cc
diff --git a/test/cctest/compiler/test-control-reducer.cc b/test/cctest/compiler/test-control-reducer.cc
index 1d9f1c6be3e8e4f1ad508bd6b5b3b51dde9498cf..81cb77a247e0a5f253d9327ce2eec40f3eac05dc 100644
--- a/test/cctest/compiler/test-control-reducer.cc
+++ b/test/cctest/compiler/test-control-reducer.cc
@@ -1261,23 +1261,6 @@ TEST(CUnusedDiamond2) {
 TEST(CDeadLoop1) {
   ControlReducerTester R;
 
-  Node* loop = R.graph.NewNode(R.common.Loop(1), R.start);
-  Branch b(R, R.p0, loop);
-  loop->ReplaceInput(0, b.if_true);  // loop is not connected to start.
-  Node* merge = R.graph.NewNode(R.common.Merge(2), R.start, b.if_false);
-  R.ReduceMergeIterative(R.start, merge);
-
-  DeadChecker dead(&R.graph);
-  dead.Check(b.if_true);
-  dead.Check(b.if_false);
-  dead.Check(b.branch);
-  dead.Check(loop);
-}
-
-
-TEST(CDeadLoop2) {
-  ControlReducerTester R;
-
   While w(R, R.p0);
   Diamond d(R, R.zero);
   // if (0) { while (p0) ; } else { }