Remove duplicate inline scaffold in 2up renderer
Summary: Ref T2009. Remove the 4 (!!) copies of this code.
Test Plan:
- Added, edited, and removed inline comments in 2up view.
- Stacked a bunch of comments on the same line and saw the JS place them correctly.
- Created an image diff and added, edited and removed inlines on it.
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T2009
Differential Revision: https://secure.phabricator.com/D12000