[turbofan] Introduce CheckUnless.

src/compiler/simplified-lowering.cc

Index: src/compiler/simplified-lowering.cc
diff --git a/src/compiler/simplified-lowering.cc b/src/compiler/simplified-lowering.cc
index 4810ede877954dcf41b204803b1e76ba822156b4..3c8dd1f336f5f48686efe9009fbee2574b47e8ea 100644
--- a/src/compiler/simplified-lowering.cc
+++ b/src/compiler/simplified-lowering.cc
@@ -1192,6 +1192,11 @@ class RepresentationSelector {
       case IrOpcode::kHeapConstant:
         return VisitLeaf(node, MachineRepresentation::kTagged);
 
+      case IrOpcode::kCheckIf:
+      case IrOpcode::kCheckUnless:
+        ProcessInput(node, 0, UseInfo::Bool());
+        ProcessRemainingInputs(node, 1);
+        return;
       case IrOpcode::kDeoptimizeIf:
       case IrOpcode::kDeoptimizeUnless:
         ProcessInput(node, 0, UseInfo::Bool());