Fix breadcrumbs in WinIE

Summary: Fixes T5902, in theory float and inline-block achieve the same thing.

Test Plan: Test Safari, IE, and Chrome crumb layouts in Phriction, Diffusion, and Maniphest.

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Maniphest Tasks: T5902

Differential Revision: https://secure.phabricator.com/D10347