The speed of light is a constant. This is the fundamental rule in relativity theory. So as crazy as it seems, the light would still be measured at 3e8m/s.
This speed is given by the reciprocal of the square root of the product of two universal constants. Since these constants do not change based on your frame of reference, the speed of light in vacuum cannot change either. This is why funny things start to happen with time and space as the relative velocity of two frames of reference approaches the speed of light.