Revert of [compiler] Drop the CompareNilIC. (patchset #4 id:60001 of https://codereview.chromium.org/1722193002/ )

Reason for revert:
Speculative revert in attempt to fix #2 crasher on canary.

Original issue's description:
> [compiler] Drop the CompareNilIC.
>
> Since both null and undefined are also marked as undetectable now, we
> can just test that bit instead of having the CompareNilIC try to collect
> feedback to speed up the general case (without the undetectable bit
> being used).
>
> Drive-by-fix: Update the type system to match the new handling of
> undetectable in the runtime.
>
> R=danno@chromium.org
>
> Committed: https://crrev.com/666aec0348c8793e61c8633dee7ad29a514239ba
> Cr-Commit-Position: refs/heads/master@{#34237}

TBR=danno@chromium.org,verwaest@chromium.org,bmeurer@chromium.org
LOG=y
BUG=chromium:589897
NOTRY=true

Review URL: https://codereview.chromium.org/1743433002

Cr-Commit-Position: refs/heads/master@{#34308}