osx: enable MathBuiltinsCall.js

[MikeHolman]

Not sure how much we care, but for example, Math.atan(10) is 1.4711276743037344 on OSX. On other platforms it equals 1.4711276743037347.

Opened as result of test failure in #4531

[obastemur]

some tips;

Test: https://github.com/Microsoft/ChakraCore/blob/master/test/AsmJs/MathBuiltinsCall.js

The test file looks useful for testing math builtins and we may compare atan result per platform if it's necessary:

var isMac = (WScript.Platform && WScript.Platform.OS == 'darwin');

The line above is to check if the host OS is a mac.