Support exotic notations for Numbers

[bartveneman]

I know these are very unlikely patterns to run into, but apparently they exist, so support for them would be nice (but definitely not required):

    numbers {
      color: rgba(1e2, .5e1, .5e0, +.25e2%);
    }

Source: https://developer.mozilla.org/en-US/docs/Web/CSS/color_value#rgb_transparency_variations

[omgovich]

Hi! I'll think about the issue. Since that's a valid value according to the specs, we should try to extend the parsers.