[builtins] Migrate Math.clz32 to a TurboFan builtin.

src/js/math.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) {
 "use strict";
 
 %CheckIsBootstrapping();
 
 // -------------------------------------------------------------------
@@ skipping 125 matching lines @@
   for (var i = 0; i < length; i++) {
     var n = arguments[i] / max;
     var summand = n * n - compensation;
     var preliminary = sum + summand;
     compensation = (preliminary - sum) - summand;
     sum = preliminary;
   }
   return %math_sqrt(sum) * max;
 }
 
-// ES6 draft 07-18-14, section 20.2.2.11
-function MathClz32JS(x) {
-  return %_MathClz32(x >>> 0);
-}
-
 // ES6 draft 09-27-13, section 20.2.2.9.
 // Cube root approximation, refer to: http://metamerist.com/cbrt/cbrt.htm
 // Using initial approximation adapted from Kahan's cbrt and 4 iterations
 // of Newton's method.
 function MathCbrt(x) {
   x = TO_NUMBER(x);
   if (x == 0 || !NUMBER_IS_FINITE(x)) return x;
   return x >= 0 ? CubeRoot(x) : -CubeRoot(-x);
 }
 
@@ skipping 41 matching lines @@
   "abs", MathAbs,
   "exp", MathExp,
   "log", MathLog,
   "atan2", MathAtan2JS,
   "pow", MathPowJS,
   "sign", MathSign,
   "asinh", MathAsinh,
   "acosh", MathAcosh,
   "atanh", MathAtanh,
   "hypot", MathHypot,
-  "clz32", MathClz32JS,
   "cbrt", MathCbrt
 ]);
 
 %SetForceInlineFlag(MathAbs);
 %SetForceInlineFlag(MathAtan2JS);
-%SetForceInlineFlag(MathClz32JS);
 %SetForceInlineFlag(MathRandom);
 %SetForceInlineFlag(MathSign);
 
 // -------------------------------------------------------------------
 // Exports
 
 utils.Export(function(to) {
   to.MathAbs = MathAbs;
   to.MathExp = MathExp;
   to.IntRandom = MathRandomRaw;
 });
 
 })