[test] Skip flaky test

TBR=yangguo@chromium.org
NOTRY=true

Bug: v8:7859
Change-Id: Ie3d21f21b12bc2d36eb1b0ea798e2d6030342492
Reviewed-on: https://chromium-review.googlesource.com/1105760
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53818}

test/cctest/cctest.status

@@ -125,6 +125,9 @@
   'test-serialize/SnapshotCreatorNoExternalReferencesCustomFail1': [FAIL],
   'test-serialize/SnapshotCreatorNoExternalReferencesCustomFail2': [FAIL],
 
+  # https://crbug.com/v8/7859
+  'test-heap/Regress538257': [SKIP],
+
   ############################################################################
   # Slow tests.
   'test-debug/CallFunctionInDebugger': [PASS, ['mode == debug', SLOW]],