This reverts commit 1ba5d5ba.

Reason for revert: Follow-up revert for b1cf1e1e

Original change's description:
> Clean up DependentCode class.
> 
> Also move some helpers there.
> 
> Bug: v8:7902
> Change-Id: I1ef3d1e8317102afae2861382e9ba60b0ef6bba4
> Reviewed-on: https://chromium-review.googlesource.com/1121461
> Commit-Queue: Georg Neis <neis@chromium.org>
> Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#54179}

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

Change-Id: I02f01f9e8f3bcea13339d4eb87eab784b16f4ad1
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7902
Reviewed-on: https://chromium-review.googlesource.com/1125681Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54194}