search: clicking on search result may not result in that page becoming the current page

Clicking on the search result in 1up may not result in that page becoming the current page (and thus being placed in the browser location).

e.g.
1. Load http://www.archive.org/stream/papersonbacterio00russrich#page/59/mode/1up/search/summary
2. Click "Page 69"
3. Page 69 becomes visible, but page 68 is at the top of the screen and /page/68 is in the browser location. Since the search result is centered and the *top* page is current there is a mismatch.

Expected:
Clicking a search result should always result in that page being the current one.

Proposed fix:
The center-most page in 1up should be the "current" page.