Convert back slashes to forward slashes in import statement.
Convert back slashes to forward slashes in import statement.

Usually an import of css is replaced with the css content, however sometimes it results in an @import statement.
Could not produce an example that generates an @import statement. In a current project of mine this happens to some css files imported from a jspm package. Not sure what triggers it (size/other references/location).
Therefor, no unit test was added

systemjs/plugin-css,systemjs/plugin-css