Try unskipping ContextSerializerContext cctest

The flaky failure is three years old, let's see how it behaves today.

Bug: v8:5920
Change-Id: Idaa71d274f937e3c6997b49e0acfe7cc88e64956
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2484571
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70600}

test/cctest/cctest.status

@@ -255,9 +255,6 @@
   # BUG(v8:8744).
   'test-cpu-profiler/FunctionCallSample': [SKIP],
 
-  # BUG(5920): Flaky crash.
-  'test-serialize/ContextSerializerContext': [PASS, ['arch == x64 and mode == debug', SKIP]],
-
   # BUG(10107): Failing flakily
   'test-cpu-profiler/Inlining2': ['arch == ia32 and mode == debug', SKIP],
   'test-cpu-profiler/CrossScriptInliningCallerLineNumbers2': ['arch == ia32 and mode == debug', SKIP],