Simplified domains: make sure full URL shows on same-doc navigations

Previously, when a same-doc navigation occurs before the user has
interacted with the page, we were simply leaving everything as it was
with the full URL showing. This worked fine until we removed the "edit
bump" (crbug.com/1101486), which involved setting the display rect on
page load to contain all of the URL except the scheme and trivial
subdomains. Now that the display rect is set on page load, we have to
make sure it's adjusted again on a same-doc navigation, in case the
URL has become longer. Otherwise the URL after the same-doc navigation
would be cut off where the previous URL ended.

Bug: 1108955
Change-Id: Id6240ef347e30ac061c4f7121b753233e6fe26d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2316792


Reviewed-by: Tommy Li <tommycli@chromium.org>
Commit-Queue: Emily Stark <estark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791470}