overwrite the page title

We need another issue for the scrolling on load.
I'm attaching the patch here for the record.

I've been exploring this and it means editing the original code from pdf.js: https://mozilla.github.io/pdf.js/

We are delivering in this module a very archaic version of that, so I'm fine with editing it. But after inheriting this module, I'm coming to understand that this is very fragile, relying on a very old piece of js code (2012), which I definitely don't want to maintain.

We need to look at ways to make this project using the last release of pdf.js, which is under active development. And that definitely should be in a major release.