Revert of [turbofan] Osr value typing + dynamic type checks on entry. (patchset #5 id:80001 of https://codereview.chromium.org/2384113002/ )

Reason for revert:
Tanks the world.

Original issue's description:
> [turbofan] Osr value typing + dynamic type checks on entry.
>
> This introduces a new OsrGuard node that is inserted during graph building
> to guard the inferred type of the OSR value.
>
> The type of the OSR value is inferred by running the typer before OSR
> deconstruction, and then taking the type from the phi that takes the
> OSR value. After the deconstruction, we throw the types away.
>
> At the moment we only support the SignedSmall OSR type and we always
> pick the tagged representation. Later, we might want to support more
> types (such as Number) and pick better representations (int32/float64).
>
> This CL also removes the OSR deconstruction tests because they build
> unrealistic graph (no effect chain, no loop termination). I considered
> adding the effect chains to the tests, but this would make the tests
> even more brittle.
>
> Committed: https://crrev.com/1f5dc90a900d222da44bee3eff171a2ba1e3c076
> Cr-Commit-Position: refs/heads/master@{#39971}

TBR=bmeurer@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review-Url: https://codereview.chromium.org/2395783002
Cr-Commit-Position: refs/heads/master@{#39985}