Use Type::Array to constant-fold Array.isArray builtin based on the
value input type. Also use it to improve type based alias analysis,
where we know that stores to an object of type Array don't affect stores
to an object of type OtherObject, and vice versa.

R=jarin@chromium.org
BUG=v8:6262

Review-Url: https://codereview.chromium.org/2819583002
Cr-Commit-Position: refs/heads/master@{#44681}