Get rid of IE hacks (\9) to prevent interfering with vite/esbuild

[gomorizsolt]

Based off my research, there are two occurrences of this hacky way of supporting older versions of IE:

• Spin
• Popover

It causes troubles in terms of bundling the project with Vite. I have already submitted a bug report and it turned out esbuild is culprit. My Q is, cannot \9 be removed from the codebase altogether to prevent interfering with esbuild's minifying process? I can no longer see the use of this hack given that [email protected] does not even support ancient versions of IE.