[PM] Retire kNetworkAlmostIdle property.

This retires the kNetworkAlmostIdle from the frame node as part of the
refactor that aims to get rid of the "bag of properties" from node impls.

BUG=910288

Change-Id: I78b7d0f03cc23b91122328d1b7eab4b1f09a3176
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1520701
Commit-Queue: Chris Hamilton <chrisha@chromium.org>
Reviewed-by: Sigurður Ásgeirsson <siggi@chromium.org>
Reviewed-by: Will Harris <wfh@chromium.org>
Auto-Submit: Chris Hamilton <chrisha@chromium.org>
Cr-Commit-Position: refs/heads/master@{#640894}
9 files changed