partial strength reduction for bit ops

We had full constant eval of these already; this adds a bunch of
degenerate cases when one argument is known to be true or false.

Change-Id: Ic0535d8a99357947fd73bd9f719eec4645dc919d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/267243
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
1 file changed