Lower simplified StringAdd to stub call.

src/compiler/js-typed-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/access-builder.h"
 #include "src/compiler/graph-inl.h"
 #include "src/compiler/js-typed-lowering.h"
 #include "src/compiler/node-aux-data-inl.h"
 #include "src/compiler/node-properties-inl.h"
 #include "src/types.h"
@@ skipping 204 matching lines @@
     NodeProperties::ReplaceEffectInput(node_, effect);
   }
 };
 
 
 Reduction JSTypedLowering::ReduceJSAdd(Node* node) {
   JSBinopReduction r(this, node);
   if (r.OneInputIs(Type::String())) {
     r.ConvertInputsToString();
     return r.ChangeToPureOperator(simplified()->StringAdd());
-  } else if (r.NeitherInputCanBe(Type::String())) {
+  }
+  if (r.NeitherInputCanBe(Type::String())) {
     r.ConvertInputsToNumber();
     return r.ChangeToPureOperator(simplified()->NumberAdd());
   }
   return NoChange();
 }
 
 
 Reduction JSTypedLowering::ReduceNumberBinop(Node* node, Operator* numberOp) {
   JSBinopReduction r(this, node);
   if (r.OneInputIs(Type::Primitive())) {
@@ skipping 378 matching lines @@
     case IrOpcode::kJSLoadProperty:
       return ReduceJSPropertyLoad(node);
     default:
       break;
   }
   return NoChange();
 }
 }
 }
 }  // namespace v8::internal::compiler