Revert "[turbofan] Polymorphic inlining - try merge map check dispatch with function call dispatch."

This reverts commit 627c440b.

Reason for revert: Likely breaks Canary.

Original change's description:
> [turbofan] Polymorphic inlining - try merge map check dispatch with function call dispatch.
> 
> This improves delta blue by about >5%. Unfortunately, this still does not help load
> and check elimination because we do not learn maps from control flow.
> 
> Change-Id: I49a97dbc40576b9bc80c87ec2b459e37ba9b4440
> Bug: v8:5267
> Reviewed-on: https://chromium-review.googlesource.com/618328
> Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
> Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#47405}

TBR=jarin@chromium.org,bmeurer@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: v8:5267
Change-Id: Id12519ae98b42b57fbef86d0685950f6c85f5082
Reviewed-on: https://chromium-review.googlesource.com/622827Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47457}