Lower StoreDataPropertyInLiteral() when storing
computed property names in object literals.

Add a new AccessMode, kStoreInLiteral. It is similar to
AccessMode::kStore but does not look
up properties on the prototype chain.

99% of all literal definitions with computed property names
end up with generic access_info because of how we count
properties. Once we fix
https://bugs.chromium.org/p/v8/issues/detail?id=5625,
they'll get lowered as well.

BUG=v8:5624

Review-Url: https://codereview.chromium.org/2619773002
Cr-Commit-Position: refs/heads/master@{#42210}