Without studying the minified code I wouldn't assume malice just yet, this could be just an inexperienced developer trying to lazily fix some browser-specific bug, or something that accidentally made it to production like you say
This reply is for everyone who has ever worked on the codebase...
Yes
Uh, yes? We were all inexperienced at some point. Just the linked file is like 300k lines of unminified code, I doubt it's all written by PHDs with 20 years of experience