[turbofan] Constant-fold concatenation of strings.

src/compiler/js-native-context-specialization.h

 // Copyright 2015 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.
 
 #ifndef V8_COMPILER_JS_NATIVE_CONTEXT_SPECIALIZATION_H_
 #define V8_COMPILER_JS_NATIVE_CONTEXT_SPECIALIZATION_H_
 
 #include "src/base/flags.h"
 #include "src/compiler/graph-reducer.h"
 #include "src/deoptimize-reason.h"
@@ skipping 35 matching lines @@
   typedef base::Flags<Flag> Flags;
 
   JSNativeContextSpecialization(Editor* editor, JSGraph* jsgraph, Flags flags,
                                 Handle<Context> native_context,
                                 CompilationDependencies* dependencies,
                                 Zone* zone);
 
   Reduction Reduce(Node* node) final;
 
  private:
+  Reduction ReduceJSAdd(Node* node);
   Reduction ReduceJSGetSuperConstructor(Node* node);
   Reduction ReduceJSInstanceOf(Node* node);
   Reduction ReduceJSOrdinaryHasInstance(Node* node);
   Reduction ReduceJSLoadContext(Node* node);
   Reduction ReduceJSLoadGlobal(Node* node);
   Reduction ReduceJSStoreGlobal(Node* node);
   Reduction ReduceJSLoadNamed(Node* node);
   Reduction ReduceJSStoreNamed(Node* node);
   Reduction ReduceJSLoadProperty(Node* node);
   Reduction ReduceJSStoreProperty(Node* node);
@@ skipping 130 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(JSNativeContextSpecialization);
 };
 
 DEFINE_OPERATORS_FOR_FLAGS(JSNativeContextSpecialization::Flags)
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_JS_NATIVE_CONTEXT_SPECIALIZATION_H_