[turbofan] Make MachineType a pair of enums.

src/compiler/select-lowering.cc

Index: src/compiler/select-lowering.cc
diff --git a/src/compiler/select-lowering.cc b/src/compiler/select-lowering.cc
index 28a5d922b799c8a3116c9c0c01f18cdbef5b50f5..0e8b36fa73ace01527a73987f483220db9050d2f 100644
--- a/src/compiler/select-lowering.cc
+++ b/src/compiler/select-lowering.cc
@@ -55,7 +55,7 @@ Reduction SelectLowering::Reduce(Node* node) {
   node->ReplaceInput(0, vthen);
   node->ReplaceInput(1, velse);
   node->ReplaceInput(2, merge);
-  NodeProperties::ChangeOp(node, common()->Phi(p.type(), 2));
+  NodeProperties::ChangeOp(node, common()->Phi(p.representation(), 2));
   return Changed(node);
 }