Make image pagination not require a page load.

Progressively enhance multi-page image navigation so that the paginated
part is changed without requiring a full page load. Currently, the url
is not updated to reflect the current page after navigation occurs, but
if desired, this functionality could be added using history.pushState.

Bug: 40207
Change-Id: Icd1cde7c62c4d462f5b697b9f49f5c08f6e7482b
Merge "Make image pagination not require a page load."