@-moz-document url-prefix() bug

[ianva]

@-moz-document url-prefix() is firefox hack, use it will output an error.

example:

@-moz-document url-prefix() {
   .test { font-size: 100%; }
}

/usr/local/lib/node_modules/css-condense/node_modules/css-stringify/index.js:143
      + node.declarations.map(this.declaration, this).join(';')
                          ^
TypeError: Cannot call method 'map' of undefined
    at Compiler.rule (/usr/local/lib/node_modules/css-condense/node_modules/css-stringify/index.js:143:27)
    at Compiler.visit (/usr/local/lib/node_modules/css-condense/node_modules/css-stringify/index.js:43:15)
    at Array.map (native)
    at Compiler.compile (/usr/local/lib/node_modules/css-condense/node_modules/css-stringify/index.js:30:32)
    at Object.module.exports [as stringify] (/usr/local/lib/node_modules/css-condense/node_modules/css-stringify/index.js:12:32)
    at compressCode (/usr/local/lib/node_modules/css-condense/index.js:55:20)
    at compress (/usr/local/lib/node_modules/css-condense/index.js:27:10)
    at Object.<anonymous> (/usr/local/lib/node_modules/css-condense/bin/cssc:51:15)
    at Module._compile (module.js:449:26)
    at Object.Module._extensions..js (module.js:467:10)

use csso will return

@-moz-document url-prefix(){.test{font-size:100%}}