Since Chronium 148, Math.tanh is now fingerprintable to link underlying OS

Math.tanh, every CSS trig function, and the Web Audio compressor all route through the host libm, so the rounding of a cosine betrays the OS a browser actually runs on. Where the leak lives across V8, Blink, and Web Audio, and what bit-for-bit reproduction of Apple’s math library takes to close it.