This CL makes sure, that logical operators (||, &&) always have return
type never. Together with a check that never is never passed as a
function argument, this prevents faulty evaluation as in !(x || y).

Before, the logical operators had a behavior similar to
(bool labels Taken, NotTaken), with a fast exit if the left-hand side
allowed shor-circuit evaluation, but returning the right-hand side
otherwise. Since we want to allow existing (a || b || c) patterns in
the codebase, this requires weakening the restriction that the left-
and right-hand side need to have the same type. Now the possibilites
are:
bool, never
never, bool
never, never
bool, bool
constexpr bool, constexpr bool

Bug: v8:8137
Change-Id: I9576b337dc4008ac58b4625e77fef4e73bcdd6e3
Reviewed-on: https://chromium-review.googlesource.com/1215162Reviewed-by: Daniel Clifford <danno@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55750}