Carry over previous document's FrameScheduler's task time on
RenderDocument's LocalFrame <-> LocalFrame swap

When RenderDocument is enabled, same-site cross-document navigations
will create a new LocalFrame instead of reusing the previous
LocalFrame. This means the total task time tracked in the previous
document's FrameSchedulerImpl won't be carried over to the new
document on subframe navigation, which is a regression. This CL makes
it so that the total task time is passed from the previous LocalFrame
to the new LocalFrame, using OldDocumentInfoForCommit.

See also: https://chromium-review.googlesource.com/c/chromium/src/+/4353252/comment/5c2b42b5_387a93fb/

Bug: 936696
Change-Id: Iaf567f3aef9b605f6e4dbe9d3f9d94cd17ab9a3e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4686375
Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Rakina Zata Amni <rakina@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1177671}