Using path-is-absolute for windows compatibility

[joshwnj]

Fixes #74 (hopefully)

[Nimelrian]

Does not work on Windows with the following setup:

└───css-modulesify-test
      ├───border.css
      ├───gulpfile.js
      ├───index.js
      ├───package.json
      └───style.css

package.json

{
  "name": "css-modulesify-test",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "browserify": "^13.3.0",
    "css-modulesify": "css-modules/css-modulesify#fix-windows-abs-path",
    "gulp": "^3.9.1"
  }
}

gulpfile.js

const browserify = require('browserify');
const cssModules = require('css-modulesify');
const gulp = require('gulp');

gulp.task('default', () => {
  browserify({
    entries: './index.js',
    debug: true,
  })
    .plugin(cssModules, {
      output: './modules.css',
    })
    .bundle()
    .pipe(gulp.dest('./bundle.js'));
});

index.js

const styles = require('./style.css');

console.log(styles.normal);

style.css

.normal {
  composes: greyBottom from './border.css';
}

border.css

.greyBottom {
  border-bottom: 1px solid #C8C8C8;
}

Error message:

C:\dev\js\css-modulesify-test>gulp
[09:13:44] Using gulpfile C:\dev\js\css-modulesify-test\gulpfile.js
[09:13:44] Starting 'default'...
[09:13:44] Finished 'default' after 14 ms
NO NODE C:\dev\js\css-modulesify-test\C:\C:\style.css C:\dev\js\css-modulesify-test\C:\C:\border.css
Error: Node does not exist: C:\dev\js\css-modulesify-test\C:\C:\style.css
    at Object.DepGraph.addDependency (C:\dev\js\css-modulesify-test\node_modules\dependency-graph\lib\dep_graph.js:87:13)
    at C:\dev\js\css-modulesify-test\node_modules\css-modulesify\file-system-loader.js:102:22
    at FileSystemLoader.fetch (C:\dev\js\css-modulesify-test\node_modules\css-modulesify\file-system-loader.js:65:14)
    at Parser.fetchImport (C:\dev\js\css-modulesify-test\node_modules\css-modules-loader-core\lib\parser.js:90:19)
    at C:\dev\js\css-modulesify-test\node_modules\css-modules-loader-core\lib\parser.js:49:31
    at Root.each (C:\dev\js\css-modulesify-test\node_modules\postcss\lib\container.js:110:22)
    at Parser.fetchAllImports (C:\dev\js\css-modulesify-test\node_modules\css-modules-loader-core\lib\parser.js:47:11)
    at Parser.plugin (C:\dev\js\css-modulesify-test\node_modules\css-modules-loader-core\lib\parser.js:35:31)
    at LazyResult.run (C:\dev\js\css-modulesify-test\node_modules\postcss\lib\lazy-result.js:270:20)
    at LazyResult.asyncTick (C:\dev\js\css-modulesify-test\node_modules\postcss\lib\lazy-result.js:185:32)
path.js:7
    throw new TypeError('Path must be a string. Received ' + inspect(path));
    ^

TypeError: Path must be a string. Received undefined
    at assertPath (path.js:7:11)
    at Object.resolve (path.js:184:7)
    at DestroyableTransform.saveFile [as _transform] (C:\dev\js\css-modulesify-test\node_modules\vinyl-fs\lib\dest\index.js:36:26)
    at DestroyableTransform.Transform._read (C:\dev\js\css-modulesify-test\node_modules\vinyl-fs\node_modules\readable-stream\lib\_stream_transform.js:184:10)
    at DestroyableTransform.Transform._write (C:\dev\js\css-modulesify-test\node_modules\vinyl-fs\node_modules\readable-stream\lib\_stream_transform.js:172:12)
    at doWrite (C:\dev\js\css-modulesify-test\node_modules\vinyl-fs\node_modules\readable-stream\lib\_stream_writable.js:237:10)
    at writeOrBuffer (C:\dev\js\css-modulesify-test\node_modules\vinyl-fs\node_modules\readable-stream\lib\_stream_writable.js:227:5)
    at DestroyableTransform.Writable.write (C:\dev\js\css-modulesify-test\node_modules\vinyl-fs\node_modules\readable-stream\lib\_stream_writable.js:194:11)
    at Readable.ondata (C:\dev\js\css-modulesify-test\node_modules\readable-stream\lib\_stream_readable.js:612:20)
    at emitOne (events.js:96:13)

Note that the paths in the error message still contain "C:\C:\