Skip slow webkit/array-iterate-backwards in arm64.debug/gc-stress mode.

test/webkit/webkit.status

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 # modification, are permitted provided that the following conditions are
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 #
 #     * Redistributions of source code must retain the above copyright
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@@ skipping 52 matching lines @@
 }],  # 'dcheck_always_on == True and arch == arm64'
 
 
 ##############################################################################
 ['gc_stress == True', {
   # Tests taking too long
   'fast/js/excessive-comma-usage': [SKIP]
 }],  # 'gc_stress == True'
 
 ['gc_stress == True and mode == debug', {
-  # Skip tests that timout with turbofan.
-  'array-iterate-backwards': [PASS, NO_VARIANTS]
+  # Skip tests that timeout.
+  'array-iterate-backwards': [SKIP]
 }],  # 'gc_stress == True and mode == debug'
 
 ##############################################################################
 ]