Revert of [turbofan] Add the StackSlot operator to turbofan.

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 dfbad85ec8b38959ffc16f6cf0f911b6cb48ac63..196760cb9ef6c2ecc08dcf92dabb123c0fb76821 100644
--- a/src/compiler/machine-operator.h
+++ b/src/compiler/machine-operator.h
@@ -102,7 +102,6 @@
 
 CheckedStoreRepresentation CheckedStoreRepresentationOf(Operator const*);
 
-MachineRepresentation StackSlotRepresentationOf(Operator const* op);
 
 // Interface for building machine-level operators. These operators are
 // machine-level but machine-independent and thus define a language suitable
@@ -306,8 +305,6 @@
   // store [base + index], value
   const Operator* Store(StoreRepresentation rep);
 
-  const Operator* StackSlot(MachineRepresentation rep);
-
   // Access to the machine stack.
   const Operator* LoadStackPointer();
   const Operator* LoadFramePointer();