Fixed single-line comment detection not recognizing line breaks as the end of the comment

I was having an issue where comment highlighting was being applied to lines following single line comments.

For example:
``` javascript
function foo(x, y) {
  // This is a comment
  return x + y;
}
```
Everything under the comment would be interpreted as a comment as well.

I just removed `\n` from the `skip` regex pattern for `jsLineComment`, and that fixed things.