Map view moves in unexpected way after deleting a page

This issue has been migrated from mozilla/webmaker-android#1987.

It was originally written by flukeout on Thu May 21 2015 and had the following description:

Steps to reproduce

• Create a new project
• Add a new page
• Zoom in a bit and center the view on the new page
• Select that page
• Tap "Delete"
• The view shifts a bit after removing the page

The view should stay where it was (same position and zoom level).