[turbofan] Boost performance of Array.prototype.shift by 4x.

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/base/compiler-specific.h"
 #include "src/base/flags.h"
 #include "src/compiler/graph-reducer.h"
@@ skipping 40 matching lines @@
                                 IterationKind kind,
                                 ArrayIteratorKind iter_kind);
   Reduction ReduceArrayIteratorNext(Node* node);
   Reduction ReduceFastArrayIteratorNext(Handle<Map> iterator_map, Node* node,
                                         IterationKind kind);
   Reduction ReduceTypedArrayIteratorNext(Handle<Map> iterator_map, Node* node,
                                          IterationKind kind);
   Reduction ReduceArrayIsArray(Node* node);
   Reduction ReduceArrayPop(Node* node);
   Reduction ReduceArrayPush(Node* node);
+  Reduction ReduceArrayShift(Node* node);
   Reduction ReduceDateNow(Node* node);
   Reduction ReduceDateGetTime(Node* node);
   Reduction ReduceGlobalIsFinite(Node* node);
   Reduction ReduceGlobalIsNaN(Node* node);
   Reduction ReduceMathAbs(Node* node);
   Reduction ReduceMathAcos(Node* node);
   Reduction ReduceMathAcosh(Node* node);
   Reduction ReduceMathAsin(Node* node);
   Reduction ReduceMathAsinh(Node* node);
   Reduction ReduceMathAtan(Node* node);
@@ skipping 62 matching lines @@
   TypeCache const& type_cache_;
 };
 
 DEFINE_OPERATORS_FOR_FLAGS(JSBuiltinReducer::Flags)
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_JS_BUILTIN_REDUCER_H_