[web] Fix emoji rendering on Chrome by getting rid of BlinkMacSystemFont

Summary: This was causing issues rendering "♥️" on Chrome for some reason.

Test Plan: Make sure the issue is fixed on Chrome, and that things look fine on Safari and Firefox

Reviewers: atul

Reviewed By: atul

Subscribers: KatPo, palys-swm, Adrian

Differential Revision: https://phabricator.ashoat.com/D1018