Fix: Viewport coords normalized w.r.t. full page

The coordinates in Viewport.rePos are normalized on the full page. In
two functions within pageview.cpp, these were treated as coordinates on
the cropped page.

CCBUG: 198427

This partially fixes the bug 198427 in the case that the cropping of the
target pages (and the pages around the target) is known at the time the
link is clicked. That is, it works if

- One uses 'Trim To Selection'
- One uses 'Trim To Margin' and has already viewed at the target
page(s).

In the case that the cropping of the page at the target is unknown, we
still end up at the wrong position.