Fix tests to match Encoding spec

See commit messages for specific changes; note this doesn't change the names to case-sensitively match the names in the Encoding spec.

Also, Encoding makes the following test problematic:

```
#data
<!DOCTYPE HTML>
<script>document.write('<meta charset="ISO-8859-' + '2">')</script>
#encoding
iso-8859-2
```

This is now a test that should return different values between the pre-parser (scanning to infinity) and the full parser! We should probably split the tests up for such things, and only allow pre-parser ones scanning to the recommended limit.