This reverts commit d14ed12e.

Reason for revert: breaks mjsunit tests in lite mode: https://ci.chromium.org/p/v8/builders/ci/V8%20Linux%20-%20arm%20-%20sim%20-%20lite/3557

Original change's description:
> [ic] Remove the check for fast prototypes in LoadIC_Uninitialized
> 
> When handling load named properties (without feedback vectors) we used
> to miss to runtimes if the prototypes aren't set. This was because we
> wanted to give the prototype a chance to become fast, since most prototypes
> start in slow mode but move to fast after the initial setup. Though this
> check is not really useful when we don't have feedback vectors, and once
> feedback vectors are allocated we will turn the prototypes fast anyway.
> 
> Bug: v8:8394, v8:8860
> Change-Id: Ib2247e5e921f6375bda65310560ac832fd0339bf
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1561316
> Commit-Queue: Mythri Alle <mythria@chromium.org>
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#60818}

TBR=mythria@chromium.org,verwaest@chromium.org

Change-Id: I28e420951483c93363e8a78621a247a7723d735f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:8394, v8:8860
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1565893Reviewed-by: Mythri Alle <mythria@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60820}