[turbofan] Introduce new Select operator to improve bounds checking.

src/compiler/verifier.cc

Index: src/compiler/verifier.cc
diff --git a/src/compiler/verifier.cc b/src/compiler/verifier.cc
index 0bae1efd357395ab515cea8261e1aaae3da3c8e6..42b582ca23581cfa04065eb60d00bee4afab21a0 100644
--- a/src/compiler/verifier.cc
+++ b/src/compiler/verifier.cc
@@ -310,6 +310,12 @@ GenericGraphVisit::Control Verifier::Visitor::Pre(Node* node) {
       CheckUpperIs(node, Type::Any());
       break;
     }
+    case IrOpcode::kSelect: {
+      CHECK_EQ(0, effect_count);
+      CHECK_EQ(0, control_count);
+      CHECK_EQ(3, value_count);
+      break;
+    }
     case IrOpcode::kPhi: {
       // Phi input count matches parent control node.
       CHECK_EQ(0, effect_count);