Port fdlibm implementation for Math.cosh.

src/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.
 
 "use strict";
 
 // This file relies on the fact that the following declarations have been made
 // in runtime.js:
 // var $Object = global.Object;
 
@@ skipping 168 matching lines @@
 
 // ES6 draft 09-27-13, section 20.2.2.34.
 function MathTrunc(x) {
   x = TO_NUMBER_INLINE(x);
   if (x > 0) return MathFloor(x);
   if (x < 0) return MathCeil(x);
   // -0, 0 or NaN.
   return x;
 }
 
-// ES6 draft 09-27-13, section 20.2.2.12.
-function MathCosh(x) {
-  if (!IS_NUMBER(x)) x = NonNumberToNumber(x);
-  if (!NUMBER_IS_FINITE(x)) return MathAbs(x);
-  return (MathExp(x) + MathExp(-x)) / 2;
-}
-
 // ES6 draft 09-27-13, section 20.2.2.33.
 function MathTanh(x) {
   if (!IS_NUMBER(x)) x = NonNumberToNumber(x);
   // Idempotent for +/-0.
   if (x === 0) return x;
   // Returns +/-1 for +/-Infinity.
   if (!NUMBER_IS_FINITE(x)) return MathSign(x);
   var exp1 = MathExp(x);
   var exp2 = MathExp(-x);
   return (exp1 - exp2) / (exp1 + exp2);
@@ skipping 156 matching lines @@
     "sqrt", MathSqrt,
     "tan", MathTan,       // implemented by third_party/fdlibm
     "atan2", MathAtan2JS,
     "pow", MathPow,
     "max", MathMax,
     "min", MathMin,
     "imul", MathImul,
     "sign", MathSign,
     "trunc", MathTrunc,
     "sinh", MathSinh,     // implemented by third_party/fdlibm
-    "cosh", MathCosh,
+    "cosh", MathCosh,     // implemented by third_party/fdlibm
     "tanh", MathTanh,
     "asinh", MathAsinh,
     "acosh", MathAcosh,
     "atanh", MathAtanh,
     "log10", MathLog10,
     "log2", MathLog2,
     "hypot", MathHypot,
     "fround", MathFroundJS,
     "clz32", MathClz32,
     "cbrt", MathCbrt,
     "log1p", MathLog1p,   // implemented by third_party/fdlibm
     "expm1", MathExpm1    // implemented by third_party/fdlibm
   ));
 
   %SetInlineBuiltinFlag(MathCeil);
   %SetInlineBuiltinFlag(MathRandom);
   %SetInlineBuiltinFlag(MathSin);
   %SetInlineBuiltinFlag(MathCos);
 }
 
 SetUpMath();