R1:9f44ee393343

Use "link.getAttribute('href')", not "link.href", to bypass dark browser magic

Summary:
Ref T13302. In at least some browsers (including Safari and Chrome), when you write this:

```
<a href="#">...</a>
```

...and then access `<that node>.href`, you get `http://local-domain-whatever.com/path/to/current/page#` back.

This is wonderful, but not what we want. Access the raw attribute value instead, which is `#` in all browsers.

Test Plan:
- In Safari, Chrome, and Firefox:
- Clicked "Edit Subtasks" from…