[turbofan] Introduce simplified operator NumberAbs.

src/compiler/js-builtin-reducer.h

 // 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.
 
 #ifndef V8_COMPILER_JS_BUILTIN_REDUCER_H_
 #define V8_COMPILER_JS_BUILTIN_REDUCER_H_
 
 #include "src/compiler/graph-reducer.h"
 
 namespace v8 {
@@ skipping 11 matching lines @@
 
 
 class JSBuiltinReducer final : public AdvancedReducer {
  public:
   explicit JSBuiltinReducer(Editor* editor, JSGraph* jsgraph);
   ~JSBuiltinReducer() final {}
 
   Reduction Reduce(Node* node) final;
 
  private:
+  Reduction ReduceMathAbs(Node* node);
   Reduction ReduceMathAtan(Node* node);
   Reduction ReduceMathAtan2(Node* node);
   Reduction ReduceMathAtanh(Node* node);
   Reduction ReduceMathCeil(Node* node);
   Reduction ReduceMathClz32(Node* node);
   Reduction ReduceMathCos(Node* node);
   Reduction ReduceMathExp(Node* node);
   Reduction ReduceMathFloor(Node* node);
   Reduction ReduceMathFround(Node* node);
   Reduction ReduceMathImul(Node* node);
@@ skipping 23 matching lines @@
 
   JSGraph* const jsgraph_;
   TypeCache const& type_cache_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_JS_BUILTIN_REDUCER_H_