[turboprop] Mark test as slow

TBR: machenbach@chromium.org
Bug: v8:10894
Change-Id: Ie36e7cb3fe8e52478d96d24aab3517fbed29a817
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2403250Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Sathya Gunasekaran  <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69810}

test/mjsunit/mjsunit.status

@@ -1207,6 +1207,9 @@
   # TODO(mythria): Reenable this when the cl that migrates deprecated maps
   # lands
   'regress/regress-932953': [FAIL],
+
+  # https://crbug.com/v8/10894
+  'math-floor-of-div': [SLOW],
 }],  # variant == turboprop
 
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