[builtins] Migrate Math.abs() to TurboFan builtins.

src/js/v8natives.js

 // 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.
 
 (function(global, utils) {
 
 %CheckIsBootstrapping();
 
 // ----------------------------------------------------------------------------
 // Imports
 
-var GlobalArray = global.Array;
 var GlobalNumber = global.Number;
 var GlobalObject = global.Object;
 var iteratorSymbol = utils.ImportNow("iterator_symbol");
 var MakeRangeError;
 var MakeSyntaxError;
 var MakeTypeError;
-var MathAbs;
 var NaN = %GetRootNaN();
 var ObjectToString = utils.ImportNow("object_to_string");
-var toStringTagSymbol = utils.ImportNow("to_string_tag_symbol");
 
 utils.Import(function(from) {
   MakeRangeError = from.MakeRangeError;
   MakeSyntaxError = from.MakeSyntaxError;
   MakeTypeError = from.MakeTypeError;
-  MathAbs = from.MathAbs;
 });
 
 // ----------------------------------------------------------------------------
 
 
 // ES6 18.2.3 isNaN(number)
 function GlobalIsNaN(number) {
   number = TO_NUMBER(number);
   return NUMBER_IS_NAN(number);
 }
@@ skipping 321 matching lines @@
 function NumberIsNaN(number) {
   return IS_NUMBER(number) && NUMBER_IS_NAN(number);
 }
 
 
 // Harmony isSafeInteger
 function NumberIsSafeInteger(number) {
   if (NumberIsFinite(number)) {
     var integral = TO_INTEGER(number);
     if (integral == number) {
-      return MathAbs(integral) <= kMaxSafeInteger;
+      return %math_abs(integral) <= kMaxSafeInteger;
     }
   }
   return false;
 }
 
 
 // ----------------------------------------------------------------------------
 
 %FunctionSetPrototype(GlobalNumber, new GlobalNumber(0));
 
@@ skipping 72 matching lines @@
   to.NumberIsNaN = NumberIsNaN;
   to.NumberIsInteger = NumberIsInteger;
   to.ObjectHasOwnProperty = GlobalObject.prototype.hasOwnProperty;
 });
 
 %InstallToContext([
   "object_value_of", ObjectValueOf,
 ]);
 
 })