Didn`t add a CSS comment to files with a custom suffix

[Nickolay Ilchenko]

1. Block have styl file with custom suffix:

* blocks/
├── block.styl
├── block.ie.styl
└── block.css

1. Run tech with option { sourceSuffixes: ['styl', 'css', 'ie.styl'] }
2. Result:

/* ../blocks/block.styl:begin */
.icon {
  width: 200px;
}
/* ../blocks/block.styl:end */
.icon
{
    color: #fff;
}

So, if styl file have custom suffix, in this case comments did not add.