`CGAbstractMethod` takes a couple boolean parameters, among others:
* `extern`: will mark the method as `unsafe` and `extern`
* `unsafe`: will wrap the method body in an `unsafe` block
Passing both as `True` should not mark it as `unsafe` twice.
Example from a generated `HTMLCollectionBinding.rs`:
Before:
```
unsafe extern fn get_length(..) -> u8 {
unsafe {
// code here
}
}
```
After
```
unsafe extern fn get_length(..) -> u8 {
// code here
}
```
Source-Repo: https://github.com/servo/servo
Source-Revision: 289decb064b44937f570fdc299de9af961296dd6