Prevent stripping <!-- htmlmin:ignore -->

I have a use case where I'd like to clean up developer code by stripping redundant and obsolete attributes, however want to keep all white space and htmlmin:ignore comments. Is this possible?

#### test code
```

...

```
### expected
```
<!-- htmlmin:ignore --><pre>...</pre><!-- htmlmin:ignore -->
<script src=/file.js>
```
### result
```
<pre>...</pre>
<script src=/file.js>
```

Reproduce the supplied HTML with the minifier and trace handling of the htmlmin:ignore comments. Check how ignored regions are removed while redundant attributes are simplified. Done means both ignore comments and the enclosed whitespace-sensitive content remain in the output while the script's redundant type attribute is still stripped.

Written by the indexing model from the issue text.