Add integration specs for emoji

@pslaughter commented in !51972 (comment 501188997)

Also, do you know if these changes have any relevant integration or feature specs? Since these modules are a bit complex and hard to change, it might be nice to make sure we have a harness like this.

If we don't I'd like to recommend following this MR up with an issue to add some specs in spec/frontend_integration. WDYT?