[turbofan] Next step towards shared operators.

src/compiler/simplified-lowering.cc

Index: src/compiler/simplified-lowering.cc
diff --git a/src/compiler/simplified-lowering.cc b/src/compiler/simplified-lowering.cc
index 74af3980ff7215adc96a40bb47efae53b7d5804d..27212f7975c71c584fa27194b670b46e20ed7ae5 100644
--- a/src/compiler/simplified-lowering.cc
+++ b/src/compiler/simplified-lowering.cc
@@ -336,15 +336,15 @@ class RepresentationSelector {
     }
   }
 
-  Operator* Int32Op(Node* node) {
+  const Operator* Int32Op(Node* node) {
     return changer_->Int32OperatorFor(node->opcode());
   }
 
-  Operator* Uint32Op(Node* node) {
+  const Operator* Uint32Op(Node* node) {
     return changer_->Uint32OperatorFor(node->opcode());
   }
 
-  Operator* Float64Op(Node* node) {
+  const Operator* Float64Op(Node* node) {
     return changer_->Float64OperatorFor(node->opcode());
   }