Fix root map not taken into account for cssFolderPath

This pull request fixes a regression introduced by commit 96c3f0591012d316db5de8325225645449ee26a7:
the root map is not taken into account for the computation of the `cssFolderPath` property in CSS templates.
This assert is not clear to me... If `CSSFolderPathTestCase.js` was removed within the test itself (line 23), why should we check?