Fix scroll when going back to initial route

[hworld]

Should fix: #1585

I added a new e2e test that sets scrollRestoration to manual. Without the fix the test correctly fails.

[posva]

I tested this fix on Firefox and the bug is still happening though... I thought you used dev but you created a new branch 👍

[posva]

Tested manually as well
@yyx990803 I cannot see anything else, can you take a look? (1 line bug fix for Firefox)

[posva]

ping @yyx990803

[djune]

@hworld
Throw an exception use IE9 test
// Fix for #1585 for Firefox window.history.replaceState({ key: getStateKey() }, '');

[JounQin]

@djune It has been fixed in #1835 which has not been released.