Partial revert of r164195 due to back/forward issues in chrome://settings

It appears that webui is dependent on a quirk in HistoryController where an
initial load in a child frame sometimes finds an existing HistoryItem in its
spot in the tree and needs to overwrite it. It's not clear to me why this is
necessary, except that it appears to involve some confluence of pushState and
reloading.

Attempts to create a test were unsuccessful. It's unclear to me whether this
bug is actually triggerable from the public web, or whether webui is doing
something crazy that regular web pages can't.

BUG=332292

Review URL: https://codereview.chromium.org/135103002

git-svn-id: svn://svn.chromium.org/blink/trunk@164924 bbb929c8-8fbe-4397-9dbb-9b2b20218538