Allow a ParseInfo without a script for %SetCode users

test/mjsunit/shared-function-tier-up-ignition.js

-// Copyright 2016 the V8 project authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-//
-// Flags: --mark-shared-functions-for-tier-up --allow-natives-syntax
-// Flags: --ignition-staging --no-turbo
-// Flags: --crankshaft --no-always-opt
-
-// If we are always or never optimizing it is useless.
-assertFalse(isAlwaysOptimize());
-assertFalse(isNeverOptimize());
-
-(function() {
-  var sum = 0;
-  var i = 0;
-  for (var i = 0; i < 5; ++i) {
-    var f = function(x) {
-      return 2 * x;
-    }
-    sum += f(i);
-
-    if (i == 1) {
-      // f must be interpreted code.
-      assertTrue(isInterpreted(f));
-
-      // Allow it to run twice (i = 0, 1), then tier-up to baseline.
-      %BaselineFunctionOnNextCall(f);
-    } else if (i == 2) {
-      // Tier-up at i = 2 should only go up to baseline.
-      assertTrue(isBaselined(f));
-
-    } else if (i == 3) {
-      // Now f must be baseline code.
-      assertTrue(isBaselined(f));
-
-      // Run two more times (i = 2, 3), then tier-up to optimized.
-      %OptimizeFunctionOnNextCall(f);
-    } else if (i == 4) {
-      // Tier-up at i = 4 should now go up to crankshaft.
-      assertTrue(isCrankshafted(f));
-    }
-  }
-})()