Fixed error:
```
src/parser.rs:308:39: 308:42 error: obsolete syntax: `:`, `&mut:`, or `&:`
src/parser.rs:308     let first_non_slash = input.find(|&:c| !matches!(c, '/' | '\\')).unwrap_or(input.len());
                                                        ^~~
note: rely on inference instead
```