This reverts commit 7f58ced7.

Reason for revert: Segfaults on Atom_x64 https://ci.chromium.org/p/v8-internal/builders/ci/v8_linux64_atom_perf/5686?

Original change's description:
> [deoptimizer] Change deopt entries into builtins
>
> While the overall goal of this commit is to change deoptimization
> entries into builtins, there are multiple related things happening:
>
> - Deoptimization entries, formerly stubs (i.e. Code objects generated
>   at runtime, guaranteed to be immovable), have been converted into
>   builtins. The major restriction is that we now need to preserve the
>   kRootRegister, which was formerly used on most architectures to pass
>   the deoptimization id. The solution differs based on platform.
> - Renamed DEOPT_ENTRIES_OR_FOR_TESTING code kind to FOR_TESTING.
> - Removed heap/ support for immovable Code generation.
> - Removed the DeserializerData class (no longer needed).
> - arm64: to preserve 4-byte deopt exits, introduced a new optimization
>   in which the final jump to the deoptimization entry is generated
>   once per Code object, and deopt exits can continue to emit a
>   near-call.
> - arm,ia32,x64: change to fixed-size deopt exits. This reduces exit
>   sizes by 4/8, 5, and 5 bytes, respectively.
>
> On arm the deopt exit size is reduced from 12 (or 16) bytes to 8 bytes
> by using the same strategy as on arm64 (recalc deopt id from return
> address). Before:
>
>  e300a002       movw r10, <id>
>  e59fc024       ldr ip, [pc, <entry offset>]
>  e12fff3c       blx ip
>
> After:
>
>  e59acb35       ldr ip, [r10, <entry offset>]
>  e12fff3c       blx ip
>
> On arm64 the deopt exit size remains 4 bytes (or 8 bytes in same cases
> with CFI). Additionally, up to 4 builtin jumps are emitted per Code
> object (max 32 bytes added overhead per Code object). Before:
>
>  9401cdae       bl <entry offset>
>
> After:
>
>  # eager deoptimization entry jump.
>  f95b1f50       ldr x16, [x26, <eager entry offset>]
>  d61f0200       br x16
>  # lazy deoptimization entry jump.
>  f95b2b50       ldr x16, [x26, <lazy entry offset>]
>  d61f0200       br x16
>  # the deopt exit.
>  97fffffc       bl <eager deoptimization entry jump offset>
>
> On ia32 the deopt exit size is reduced from 10 to 5 bytes. Before:
>
>  bb00000000     mov ebx,<id>
>  e825f5372b     call <entry>
>
> After:
>
>  e8ea2256ba     call <entry>
>
> On x64 the deopt exit size is reduced from 12 to 7 bytes. Before:
>
>  49c7c511000000 REX.W movq r13,<id>
>  e8ea2f0700     call <entry>
>
> After:
>
>  41ff9560360000 call [r13+<entry offset>]
>
> Bug: v8:8661,v8:8768
> Change-Id: I13e30aedc360474dc818fecc528ce87c3bfeed42
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2465834
> Commit-Queue: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
> Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#70597}

TBR=ulan@chromium.org,rmcilroy@chromium.org,jgruber@chromium.org,tebbi@chromium.org

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

Bug: v8:8661,v8:8768,chromium:1140165
Change-Id: I3df02ab42f6e02233d9f6fb80e8bb18f76870d91
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2485504Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70649}