Summary:
Fixes T12779. Currently, we scroll down if the midline of the changeset is above the midline of the viewport.
This rule can cause us to scroll improperly when loading changesets //after// jumping to their anchors, since the changeset we want to look at will likely have a midpoint above the document midline. That is, we follow an anchor to `X.c`, then it loads, then we scroll past it.
Instead, scroll only if the changeset is (almost) entirely above the viewport.
Test Plan:
Followed an anchor to `PHUIFeedStoryExample`:
{F4984154}
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T12779
Differential Revision: https://secure.phabricator.com/D18052
d161a07781