[llvm] [WebAssembly] Add fold support for dot (PR #151775)

[Jasmine Tang via llvm-commits]

badumbatish wrote:

> Out of curiosity, is it possible to do this as a tablegen pattern? Not that it's necessarily the right thing to do, just wondering if it's easy to do or not!

I actually didn't think that tablegen can handle identical arguments in a pattern, i just tried it out just now and i think i might be able to make it work

https://github.com/llvm/llvm-project/pull/151775