[tests] Fix assertUnoptimized() when --deopt-every-n-times flag is used.

Basically, with --deopt-every-n-times flag all bets are off since
the functions can be optimized and deoptimized at any time.

BUG=v8:5890

Review-Url: https://codereview.chromium.org/2655263004
Cr-Commit-Position: refs/heads/master@{#42735}

test/mjsunit/mjsunit.js

@@ -500,6 +500,12 @@ var isTurboFanned;
     assertFalse((opt_status & V8OptimizationStatus.kAlwaysOptimize) !== 0,
                 "test does not make sense with --always-opt");
     assertTrue((opt_status & V8OptimizationStatus.kIsFunction) !== 0, name_opt);
+    if ((opt_status & V8OptimizationStatus.kMaybeDeopted) !== 0) {
+      // When --deopt-every-n-times flag is specified it's no longer guaranteed
+      // that particular function is still deoptimized, so keep running the test
+      // to stress test the deoptimizer.
+      return;
+    }
     assertFalse((opt_status & V8OptimizationStatus.kOptimized) !== 0, name_opt);
   }