[builtins] Migrate Math.log to TurboFan.

src/js/math.js

Index: src/js/math.js
diff --git a/src/js/math.js b/src/js/math.js
index 5d889674f6f827fdda72fe02adc1ff26ccaec309..e9a8daef40c7421207337a37fba7bd372d8618d7 100644
--- a/src/js/math.js
+++ b/src/js/math.js
@@ -43,11 +43,6 @@ function MathExp(x) {
   return %MathExpRT(TO_NUMBER(x));
 }
 
-// ECMA 262 - 15.8.2.10
-function MathLog(x) {
-  return %_MathLogRT(TO_NUMBER(x));
-}
-
 // ECMA 262 - 15.8.2.13
 function MathPowJS(x, y) {
   return %_MathPow(TO_NUMBER(x), TO_NUMBER(y));
@@ -93,9 +88,9 @@ function MathAsinh(x) {
   x = TO_NUMBER(x);
   // Idempotent for NaN, +/-0 and +/-Infinity.
   if (x === 0 || !NUMBER_IS_FINITE(x)) return x;
-  if (x > 0) return MathLog(x + %math_sqrt(x * x + 1));
+  if (x > 0) return %math_log(x + %math_sqrt(x * x + 1));
   // This is to prevent numerical errors caused by large negative x.
-  return -MathLog(-x + %math_sqrt(x * x + 1));
+  return -%math_log(-x + %math_sqrt(x * x + 1));
 }
 
 // ES6 draft 09-27-13, section 20.2.2.3.
@@ -104,7 +99,7 @@ function MathAcosh(x) {
   if (x < 1) return NaN;
   // Idempotent for NaN and +Infinity.
   if (!NUMBER_IS_FINITE(x)) return x;
-  return MathLog(x + %math_sqrt(x + 1) * %math_sqrt(x - 1));
+  return %math_log(x + %math_sqrt(x + 1) * %math_sqrt(x - 1));
 }
 
 // ES6 draft 09-27-13, section 20.2.2.7.
@@ -114,7 +109,7 @@ function MathAtanh(x) {
   if (x === 0) return x;
   // Returns NaN for NaN and +/- Infinity.
   if (!NUMBER_IS_FINITE(x)) return NaN;
-  return 0.5 * MathLog((1 + x) / (1 - x));
+  return 0.5 * %math_log((1 + x) / (1 - x));
 }
 
 // ES6 draft 09-27-13, section 20.2.2.17.
@@ -199,7 +194,6 @@ utils.InstallFunctions(GlobalMath, DONT_ENUM, [
   "random", MathRandom,
   "abs", MathAbs,
   "exp", MathExp,
-  "log", MathLog,
   "atan2", MathAtan2JS,
   "pow", MathPowJS,
   "sign", MathSign,