[turbofan] Enable typed lowering of string addition.

src/compiler/simplified-operator.cc

 // Copyright 2012 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-operator.h"
 
 #include "src/base/lazy-instance.h"
 #include "src/compiler/opcodes.h"
 #include "src/compiler/operator.h"
 #include "src/types-inl.h"
@@ skipping 156 matching lines @@
   V(NumberSubtract, Operator::kNoProperties, 2)         \
   V(NumberMultiply, Operator::kCommutative, 2)          \
   V(NumberDivide, Operator::kNoProperties, 2)           \
   V(NumberModulus, Operator::kNoProperties, 2)          \
   V(NumberToInt32, Operator::kNoProperties, 1)          \
   V(NumberToUint32, Operator::kNoProperties, 1)         \
   V(PlainPrimitiveToNumber, Operator::kNoProperties, 1) \
   V(StringEqual, Operator::kCommutative, 2)             \
   V(StringLessThan, Operator::kNoProperties, 2)         \
   V(StringLessThanOrEqual, Operator::kNoProperties, 2)  \
-  V(StringAdd, Operator::kNoProperties, 2)              \
   V(ChangeTaggedToInt32, Operator::kNoProperties, 1)    \
   V(ChangeTaggedToUint32, Operator::kNoProperties, 1)   \
   V(ChangeTaggedToFloat64, Operator::kNoProperties, 1)  \
   V(ChangeInt32ToTagged, Operator::kNoProperties, 1)    \
   V(ChangeUint32ToTagged, Operator::kNoProperties, 1)   \
   V(ChangeFloat64ToTagged, Operator::kNoProperties, 1)  \
   V(ChangeBoolToBit, Operator::kNoProperties, 1)        \
   V(ChangeBitToBool, Operator::kNoProperties, 1)        \
   V(ObjectIsSmi, Operator::kNoProperties, 1)            \
   V(ObjectIsNonNegativeSmi, Operator::kNoProperties, 1)
@@ skipping 101 matching lines @@
         Operator1<Type>(IrOpcode::k##Name, Operator::kNoThrow | properties,    \
                         #Name, value_input_count, 1, control_input_count,      \
                         output_count, 1, 0, access);                           \
   }
 ACCESS_OP_LIST(ACCESS)
 #undef ACCESS
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8