[turbofan] Make MachineType a pair of enums.

src/compiler/diamond.h

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_COMPILER_DIAMOND_H_
 #define V8_COMPILER_DIAMOND_H_
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph.h"
 #include "src/compiler/node.h"
@@ skipping 31 matching lines @@
   void Nest(Diamond& that, bool if_true) {
     if (if_true) {
       branch->ReplaceInput(1, that.if_true);
       that.merge->ReplaceInput(0, merge);
     } else {
       branch->ReplaceInput(1, that.if_false);
       that.merge->ReplaceInput(1, merge);
     }
   }
 
-  Node* Phi(MachineType machine_type, Node* tv, Node* fv) {
-    return graph->NewNode(common->Phi(machine_type, 2), tv, fv, merge);
+  Node* Phi(MachineRepresentation rep, Node* tv, Node* fv) {
+    return graph->NewNode(common->Phi(rep, 2), tv, fv, merge);
   }
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_DIAMOND_H_