Initialize CodeStubInterfaceDescriptor in the constructor.

src/compiler/simplified-lowering.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/simplified-lowering.h"
 
 #include "src/base/bits.h"
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph-inl.h"
 #include "src/compiler/node-properties-inl.h"
@@ skipping 834 matching lines @@
   const ElementAccess& access = ElementAccessOf(node->op());
   WriteBarrierKind kind = ComputeWriteBarrierKind(
       access.base_is_tagged, access.machine_type, access.type);
   node->set_op(machine_.Store(access.machine_type, kind));
   node->ReplaceInput(1, ComputeIndex(access, node->InputAt(1)));
 }
 
 
 void SimplifiedLowering::DoStringAdd(Node* node) {
   StringAddStub stub(zone()->isolate(), STRING_ADD_CHECK_NONE, NOT_TENURED);
-  CodeStubInterfaceDescriptor d;
-  stub.InitializeInterfaceDescriptor(&d);
+  CodeStubInterfaceDescriptor d(&stub);
   CallDescriptor::Flags flags = CallDescriptor::kNoFlags;
   CallDescriptor* desc = Linkage::GetStubCallDescriptor(&d, 0, flags, zone());
   node->set_op(common()->Call(desc));
   node->InsertInput(zone(), 0, jsgraph()->HeapConstant(stub.GetCode()));
   node->AppendInput(zone(), jsgraph()->UndefinedConstant());
   node->AppendInput(zone(), graph()->start());
   node->AppendInput(zone(), graph()->start());
 }
 
 
@@ skipping 33 matching lines @@
 void SimplifiedLowering::DoStringLessThanOrEqual(Node* node) {
   node->set_op(machine()->IntLessThanOrEqual());
   node->ReplaceInput(0, StringComparison(node, true));
   node->ReplaceInput(1, jsgraph()->SmiConstant(EQUAL));
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8