Do not retry failed attempts to retry scrolls.

Bug:3174399

If the page requests to scroll beyond the edge of the
screen, we send a message to try again on a draw, in case
our picture is out of date and the page should be larger.
However, sometimes we get stuck in a loop of retrying the
same scroll position over and over again.  End this loop.

Change-Id: I53fcd4c2fa70c7ef63d4537d8b24eabb6b924b0b