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

test/mjsunit/array-shift5.js

+// Copyright 2017 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.
+
+// Flags: --allow-natives-syntax
+
+(function() {
+  function doShift(a) { return a.shift(); }
+
+  function test() {
+    var a = [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16];
+    assertEquals(0, doShift(a));
+    assertEquals([1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16], a);
+  }
+
+  test();
+  test();
+  %OptimizeFunctionOnNextCall(doShift);
+  test();
+})();
+
+(function() {
+  function doShift(a) { return a.shift(); }
+
+  function test() {
+    var a = [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16.1];
+    assertEquals(0, doShift(a));
+    assertEquals([1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16.1], a);
+  }
+
+  test();
+  test();
+  %OptimizeFunctionOnNextCall(doShift);
+  test();
+})();
+
+(function() {
+  function doShift(a) { return a.shift(); }
+
+  function test() {
+    var a = [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,"16"];
+    assertEquals(0, doShift(a));
+    assertEquals([1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,"16"], a);
+  }
+
+  test();
+  test();
+  %OptimizeFunctionOnNextCall(doShift);
+  test();
+})();