Go 1.18 beta 1 is out. That means it's time to start working toward adding support to GopherJS.

• Compile and execute fuzz targets like normal tests. Detect and execute fuzz targets as tests #1132
• Re-enable encoding/xml tests once generics are supported. Moved to GopherJS generics support #1013.
• Generate explicit errors when encountering typeparams.
• Cleanup overlays that are not necessary in 1.18.
• syscall/js: Remove Wrapper interface.