Remove the last use of FrameLoadTypeReplace.

The suggestion next to that use (that we should try using lockBackForwardList instead) appears to work.

BUG=none

Review URL: https://chromiumcodereview.appspot.com/20059003

git-svn-id: svn://svn.chromium.org/blink/trunk@155019 bbb929c8-8fbe-4397-9dbb-9b2b20218538