[turbofan] Add the StackSlot operator to turbofan.

src/compiler/raw-machine-assembler.h

Index: src/compiler/raw-machine-assembler.h
diff --git a/src/compiler/raw-machine-assembler.h b/src/compiler/raw-machine-assembler.h
index 316eb4fa6ff95871046cd2b89b33ca41f4d4340b..fda449ab4b9b2f1c8e3974eaef587f3f431fda04 100644
--- a/src/compiler/raw-machine-assembler.h
+++ b/src/compiler/raw-machine-assembler.h
@@ -79,6 +79,9 @@ class RawMachineAssembler {
   Node* Int32Constant(int32_t value) {
     return AddNode(common()->Int32Constant(value));
   }
+  Node* StackSlot(MachineRepresentation rep) {
+    return AddNode(machine()->StackSlot(rep));
+  }
   Node* Int64Constant(int64_t value) {
     return AddNode(common()->Int64Constant(value));
   }