[turbofan] Make MachineType a pair of enums.

src/compiler/js-builtin-reducer.cc

Index: src/compiler/js-builtin-reducer.cc
diff --git a/src/compiler/js-builtin-reducer.cc b/src/compiler/js-builtin-reducer.cc
index 3e06c4f6f557fb8e9ce18de96f2d522a172e57f0..a7a7da57cd63db3d071fe1387d8137b533f0eb32 100644
--- a/src/compiler/js-builtin-reducer.cc
+++ b/src/compiler/js-builtin-reducer.cc
@@ -107,7 +107,7 @@ Reduction JSBuiltinReducer::ReduceMathMax(Node* node) {
     for (int i = 1; i < r.GetJSCallArity(); i++) {
       Node* const input = r.GetJSCallInput(i);
       value = graph()->NewNode(
-          common()->Select(kMachNone),
+          common()->Select(MachineRepresentation::kNone),
           graph()->NewNode(simplified()->NumberLessThan(), input, value), value,
           input);
     }