asm2wasm not folding away some redundant type coercions

Spotted at lot of (i32.shr_u <exp> 0) operations. Most are probably a remnant of asm.js style and should be removed?

For example: (i32.gt_u (i32.shr_u (get_local $i3) (i32.const 0)) (i32.shr_u (get_local $i1) (i32.const 0))))

[kripken]

Yes, we should remove those. What source code led to them?

Emscripten generated asm.js for the zlib benchmark. This example looks like asm.js if (i3 >>> 0 > i1 >>> 0) ... Any asm.js unsigned operators might has similar issues.

[kripken]

I see, thanks, looks like for calls and returns we look through the coercions, but for comparisons specifically we don't. Looking into that now.

[kripken]

Ok, the issue wasn't comparisons, but rather that we had the look-through logic for |0 but not >>>0. Fixed on master. Thanks again for filing!

[kripken]

Forgot to add the issue # in the commit, it was this: 2654fe2