Add MachineSignature, which is an encapsulation of the machine types for parameters and return valu…

src/compiler/machine-operator.h

Index: src/compiler/machine-operator.h
diff --git a/src/compiler/machine-operator.h b/src/compiler/machine-operator.h
index 402d48937a26b0b5321b2bc074cabb21e50267bc..9119ed6576fbaf3b39d0b97a2e928c85b75bda90 100644
--- a/src/compiler/machine-operator.h
+++ b/src/compiler/machine-operator.h
@@ -31,7 +31,7 @@ struct StoreRepresentation {
 // for generating code to run on architectures such as ia32, x64, arm, etc.
 class MachineOperatorBuilder {
  public:
-  explicit MachineOperatorBuilder(Zone* zone, MachineType word = pointer_rep())
+  explicit MachineOperatorBuilder(Zone* zone, MachineType word = kMachPtr)
       : zone_(zone), word_(word) {
     CHECK(word == kRepWord32 || word == kRepWord64);
   }
@@ -156,10 +156,6 @@ class MachineOperatorBuilder {
   inline bool is64() const { return word_ == kRepWord64; }
   inline MachineType word() const { return word_; }
 
-  static inline MachineType pointer_rep() {
-    return kPointerSize == 8 ? kRepWord64 : kRepWord32;
-  }
-
 #undef WORD_SIZE
 #undef UNOP
 #undef BINOP