GitLab

Start removing UseSubframeNavigationEntries from tests.

This mode is always enabled now, so we can remove the code for handling
when it is disabled.  This CL starts with the easy cases in tests.

BUG=236848
TEST=Tests still pass.
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation

Review-Url: https://codereview.chromium.org/2616673002
Cr-Commit-Position: refs/heads/master@{#441445}