[turbofan] Introduce a dedicated CheckMaps simplified operator.

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 9e1cf22543af90ff5929e016b0955e4ed84da551..46cf22c2e60748927e4e49ff1e279df2eeb00b4c 100644
--- a/src/compiler/simplified-lowering.cc
+++ b/src/compiler/simplified-lowering.cc
@@ -2226,6 +2226,7 @@ class RepresentationSelector {
         }
         return;
       }
+      case IrOpcode::kCheckMaps:
       case IrOpcode::kTransitionElementsKind: {
         VisitInputs(node);
         return SetOutput(node, MachineRepresentation::kNone);