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

This reverts commit 4cee9fbc.

Reason for revert: Breaks on clusterfuzz.

Original change's description:
> Reland "[turbofan] Polymorphic inlining - try merge map check dispatch with function call dispatch."
> 
> This reverts commit 57af6811.
> 
> This adds the checkpoint between the call and the polymorphic load.
> I thought that JSCall with constant target cannot cause eager deopt,
> but Canary seems to disagree (http://crbug.com/718019).
> 
> Bug: v8:5267,chromium:718019
> Change-Id: I552b850db6beb93e733b371ad0e7204513da1dc4
> Reviewed-on: https://chromium-review.googlesource.com/622867
> Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#47521}

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

Change-Id: Ib333883fa27b79fcd766c33997cb0ce46547bb94
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:5267, chromium:718019
Reviewed-on: https://chromium-review.googlesource.com/628076Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47539}