This CL ensures that the browser will not sanitize these two types of
URLs. This fixes an issue with PlzNavigate where we could not go back to
about:blank/#foo due to some discrepancy between the url in the
FrameNavigationEntry & the url stored in the PageState of the same
entry.

BUG=575210

Review-Url: https://codereview.chromium.org/2644133002
Cr-Commit-Position: refs/heads/master@{#445525}