Revert "[test] Skip test on gc fuzzer"

This reverts commit 2148d827.

Reason for revert: bug was fixed

Original change's description:
> [test] Skip test on gc fuzzer
> 
> TBR=marja@chromium.org
> 
> Bug: v8:8286
> Change-Id: I862d557c22e373c81171f0bb33b23d37157fbccd
> Reviewed-on: https://chromium-review.googlesource.com/c/1273120
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Commit-Queue: Michael Achenbach <machenbach@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#56527}

TBR=machenbach@chromium.org,marja@chromium.org

Change-Id: I9bf0632815acdd1ea29f5e622e8313b061ddd20e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:8286
Reviewed-on: https://chromium-review.googlesource.com/c/1275805Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56548}

test/mjsunit/mjsunit.status

@@ -718,9 +718,6 @@
   'regress/regress-trap-allocation-memento': [PASS, FAIL],
   'regress/regress-unlink-closures-on-deopt': [PASS, FAIL],
   'shared-function-tier-up-turbo': [PASS, FAIL],
-
-  # https://crbug.com/v8/8286
-  'harmony/weakrefs/basics': [SKIP],
 }],  # 'gc_fuzzer'
 
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