The Math.pow implementation calls libm's pow. The ISO C and ES5.1
standards differ on some special cases of pow. jerry-libm is already
ES5.1 conform, but system libm libraries on Linux and Windows aren't.
Math.pow(NaN, +/-0.0) is NaN on Windows and Linux with system libm,
but should be 1.0 according to ES5.1 / 15.8.2.13.
This patch handles this special case in Math.pow instead of calling pow of libm.
JerryScript-DCO-1.0-Signed-off-by: Csaba Osztrogonác [email protected]