[test] Skip tests failing on gc fuzzer

Temporarily skipping tests until a fix has landed.

TBR=ofrobots@google.com
NOTRY=true

Bug: v8:7313
Change-Id: I9d55f1ba190ee8104b90fd80c4b1de05508475e5
Reviewed-on: https://chromium-review.googlesource.com/888642
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50900}

test/mjsunit/mjsunit.status

@@ -647,6 +647,12 @@
 
   # Fails allocation on tsan.
   'es6/classes': [PASS, ['tsan', SKIP]],
+
+  # BUG(v8:7313).
+  'regress/regress-crbug-474297': [SKIP],
+  'regress/regress-crbug-491062': [SKIP],
+  'regress/regress-crbug-505007-1': [SKIP],
+  'regress/regress-crbug-506443': [SKIP],
 }],  # 'gc_fuzzer'
 
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