Remember previous page's position

[Huang-Libo]

When I click the back button on toolbar, I found that the previous page is not at the origin position, it seems reloaded and return to the top of the page, I think it's better to remember current page's position when the page is pushed to next page.

[scj643]

If we could get the content offset of the scroll view, or use JavaScript to get and set the scroll position and save that we could do this.