Fold a Select that negates a boolean value, i.e. returning true in the
false case and vice versa, into Branch users, similar to what we already
do for Branch nodes with BooleanNot inputs.

BUG=v8:5267

Review-Url: https://codereview.chromium.org/2308303003
Cr-Commit-Position: refs/heads/master@{#39149}