cmd/compile: type checker (types2) and compiler phase (types) don't agree on what are legal shifts

The following code

var s int
var _ = 1 << ((-1 << s) + 1)

is permitted by the type checker (types2), but runs into a lower-level compiler error (playground):

invalid operation: -1 << s + uint(1) (mismatched types int and uint)

The following code

var s int
var _ = 1 << ((-1 << s) + int(1))

is accepted (playground).

This is particularly odd because in the first example, one would expect the right-most one to be typed as int.

This should be addressed after #77117 is resolved. Requiring that the -1 must fit into an int would likely address this.

Also related: #79252

Change https://go.dev/cl/847765 mentions this issue: go/types, types2: report error for oversized non-constant shift counts

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