Fix a test

Bug: v8:12111
Change-Id: Iaee1f4273c9e7f273bd76ffba5fc60d7507a833d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3097450Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#76336}

test/mjsunit/regress/regress-347914.js

@@ -46,7 +46,7 @@ assertInstanceof = function assertInstanceof(obj, type) { if (!(obj instanceof t
 assertDoesNotThrow = function assertDoesNotThrow(code, name_opt) { try { if (typeof code == 'function') { code(); } else { eval(code); } } catch (e) { fail("threw an exception: ", e.message || e, name_opt); } };
 assertUnreachable = function assertUnreachable(name_opt) { var message = "Fail" + "ure: unreachable"; if (name_opt) { message += " - " + name_opt; } };
 var OptimizationStatus;
-try { OptimizationStatus = new Function("fun", "sync", "return %GetOptimizationStatus(fun, sync);"); } catch (e) { OptimizationStatus = function() { } }
+try { OptimizationStatus = new Function("fun", "sync", "if (sync) %WaitForBackgroundOptimization(); return %GetOptimizationStatus(fun);"); } catch (e) { OptimizationStatus = function() { } }
 assertUnoptimized = function assertUnoptimized(fun, sync_opt, name_opt) { if (sync_opt === undefined) sync_opt = ""; assertTrue(OptimizationStatus(fun, sync_opt) != 1, name_opt); }
 assertOptimized = function assertOptimized(fun, sync_opt, name_opt) { if (sync_opt === undefined) sync_opt = "";  assertTrue(OptimizationStatus(fun, sync_opt) != 2, name_opt); }
 triggerAssertFalse = function() { }