Refine durable column class toggling
Summary: don't bother with margin class if column isn't visible. Ref T8151.
Test Plan:
using chrome with trackpad
- loaded home with toggled off column - noted no margin class erroneously applied
- toggled column off and on - correct
- loaded home with toggled on column - correct
- toggled column off and on - correct
Reviewers: epriestley
Reviewed By: epriestley
Subscribers: Korvin, epriestley
Maniphest Tasks: T8151
Differential Revision: https://secure.phabricator.com/D12795