Skip regress-trap-allocation-memento in gc_stress

This test requires its objects to live in new space, so running it
through gc stress runs just makes it susceptible to flakiness, as
was recently seen when turning on the --harmony-string-padding
flag (which just adds an extra JS file to the bootstrapper sequence).

TBR=ishell@chromium.org, jkummerow@chromium.org

Review-Url: https://codereview.chromium.org/2597543002 .
Cr-Commit-Position: refs/heads/master@{#41876}

test/mjsunit/mjsunit.status

@@ -188,6 +188,7 @@
   'opt-elements-kind': [SKIP],
   'osr-elements-kind': [SKIP],
   'regress/regress-crbug-137689': [SKIP],
+  'regress/regress-trap-allocation-memento': [SKIP],
   'regress/regress-165637': [SKIP],
   'regress/regress-2249': [SKIP],
   'regress/regress-4121': [SKIP],