Revert "[d8] Use predictable platform if --predictable is passed"

This reverts commit e2016cf0.

Reason for revert: TSan issues: https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20TSAN%20-%20isolates/16209

Original change's description:
> [d8] Use predictable platform if --predictable is passed
>
> We currently only use the predictable platform if --verify-predictable
> is passed, which is confusing and not following the comment on the
> --predictable flag ("enable predictable mode").
>
> This CL fixes that and makes --verify-predictable imply --predictable to
> also allow to only pass --verify-predictable.
>
> R=​ahaas@chromium.org
> CC=​mlippautz@chromium.org
>
> Bug: v8:11879
> Change-Id: Ifb9683ddc4fab374ce519169533c90244175bb48
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3094010
> Reviewed-by: Andreas Haas <ahaas@chromium.org>
> Commit-Queue: Clemens Backes <clemensb@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#76305}

Bug: v8:11879
Change-Id: I8a76c1d1dcfefd296b9cca959192af63aa1219bb
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3097282
Auto-Submit: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#76306}

src/d8/d8.cc

@@ -5027,7 +5027,7 @@ int Shell::Main(int argc, char* argv[]) {
       options.thread_pool_size, v8::platform::IdleTaskSupport::kEnabled,
       in_process_stack_dumping, std::move(tracing));
   g_default_platform = g_platform.get();
-  if (i::FLAG_predictable) {
+  if (i::FLAG_verify_predictable) {
     g_platform = MakePredictablePlatform(std::move(g_platform));
   }
   if (options.stress_delay_tasks) {

src/flags/flag-definitions.h

@@ -2115,7 +2115,6 @@ DEFINE_NEG_IMPLICATION(single_threaded_gc, stress_concurrent_allocation)
 
 DEFINE_BOOL(verify_predictable, false,
             "this mode is used for checking that V8 behaves predictably")
-DEFINE_IMPLICATION(verify_predictable, predictable)
 DEFINE_INT(dump_allocations_digest_at_alloc, -1,
            "dump allocations digest each n-th allocation")