[heap] Make OutOfMemoryIneffectiveGC test more robust.

No-Try: true
Bug: chromium:824214
TBR: hpayer@chromium.org
Change-Id: I8095da413b5ca0ebba65b264b7310afd88d7a499
Reviewed-on: https://chromium-review.googlesource.com/984872
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52289}

test/cctest/heap/test-heap.cc

@@ -5963,7 +5963,7 @@ UNINITIALIZED_TEST(OutOfMemoryIneffectiveGC) {
         HandleScope inner_scope(i_isolate);
         factory->NewFixedArray(30000, TENURED);
       }
-      CHECK_GE(heap->tracer()->AverageMarkCompactMutatorUtilization(), 0.2);
+      CHECK_GE(heap->tracer()->AverageMarkCompactMutatorUtilization(), 0.09);
     }
   }
   isolate->Dispose();