Support proper same-page transition

This modification records the fact that a history entry was created by means of a same-page transition. This, in turn will help identify a navigation event as a same-page transition when the user navigates back/forward.

This PR is dependent upon the fix for #7602 (#7613) and upon pushState for proper functioning. If #7613 or pushState support is absent, then the following sequence will not have a transition:

start --transition--> other --transition--> same <--transition-- back --transition--> forward <--**no-transition**-- back

This is a known limitation of using hashchange only. It is a limitation that is currently also present.