[turbofan] Mark operator constructors as const in MachineOperatorBuilder.

src/compiler/machine-operator.cc

 // Copyright 2014 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.
 
 #include "src/compiler/machine-operator.h"
 
 #include "src/base/lazy-instance.h"
 #include "src/compiler/opcodes.h"
 #include "src/compiler/operator.h"
 
@@ skipping 176 matching lines @@
     LAZY_INSTANCE_INITIALIZER;
 
 
 MachineOperatorBuilder::MachineOperatorBuilder(MachineType word)
     : impl_(kImpl.Get()), word_(word) {
   DCHECK(word == kRepWord32 || word == kRepWord64);
 }
 
 
 #define PURE(Name, properties, input_count, output_count) \
-  const Operator* MachineOperatorBuilder::Name() { return &impl_.k##Name; }
+  const Operator* MachineOperatorBuilder::Name() const {  \
+    return &impl_.k##Name;                                \
+  }
 PURE_OP_LIST(PURE)
 #undef PURE
 
 
-const Operator* MachineOperatorBuilder::Load(LoadRepresentation rep) {
+const Operator* MachineOperatorBuilder::Load(LoadRepresentation rep) const {
   switch (rep) {
 #define LOAD(Type) \
   case k##Type:    \
     return &impl_.k##Load##Type;
     MACHINE_TYPE_LIST(LOAD)
 #undef LOAD
 
     default:
       break;
   }
   UNREACHABLE();
   return NULL;
 }
 
 
-const Operator* MachineOperatorBuilder::Store(StoreRepresentation rep) {
+const Operator* MachineOperatorBuilder::Store(StoreRepresentation rep) const {
   switch (rep.machine_type()) {
 #define STORE(Type)                                     \
   case k##Type:                                         \
     switch (rep.write_barrier_kind()) {                 \
       case kNoWriteBarrier:                             \
         return &impl_.k##Store##Type##NoWriteBarrier;   \
       case kFullWriteBarrier:                           \
         return &impl_.k##Store##Type##FullWriteBarrier; \
     }                                                   \
     break;
     MACHINE_TYPE_LIST(STORE)
 #undef STORE
 
     default:
       break;
   }
   UNREACHABLE();
   return NULL;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8