html.js: handle links without href attributes

``<a name="">…</a>`` is valid HTML but was causing a type error:

```
[TypeError: Cannot call method 'split' of undefined]
```

This change simply skips such links
ucss.js: ensure doneCallback is defined before it can be called

analyze() could call doneCallback() in several places before it was
certain to be defined
html.js: log the current page being loaded