use url-prefix instead of regexp

[Crystal-RainSlide]

For

Stylus-Dark/stylus-dark.user.css

Line 12 in 4e38700

@-moz-document regexp("chrome-extension://.*"),

Stylus-Dark/stylus-dark.user.css

Line 13 in 4e38700

regexp("moz-extension://.*") {

regexp("chrome-extension://.*"),
regexp("moz-extension://.*")

can be replaced by:

url-prefix("chrome-extension://"),
url-prefix("moz-extension://")

Or:

regexp("(?:chrome|moz)-extension:\/\/.+")