[Test] Re-enable math-floor-global.js on gc-stress

Should no longer be flaky since bug is fixed.

BUG=v8:8964
TBR=machenbach@chromium.org

Change-Id: I3fc124aca8bcfc16ddf7560d48d84dc01d4ce332
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1564069Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Auto-Submit: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60833}

test/mjsunit/mjsunit.status

@@ -962,9 +962,6 @@
     # skip assertion tests since the stack trace is broken if mjsunit is
     # included in the snapshot
     'mjsunit-assertion-error' : [SKIP],
-
-    # https://crbug.com/v8/8964
-    'compiler/math-floor-global': [PASS, ['gc_stress', SKIP]]
 }], # no_harness
 
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