Make deserialize-script-id test more robust.

test/mjsunit/deserialize-script-id.js

Index: test/mjsunit/deserialize-script-id.js
diff --git a/test/mjsunit/deserialize-script-id.js b/test/mjsunit/deserialize-script-id.js
index 83658126bc072c530bf0895622065831ed9f9774..5dca9f353abcc26f98f43cf136cf27a5a0591114 100644
--- a/test/mjsunit/deserialize-script-id.js
+++ b/test/mjsunit/deserialize-script-id.js
@@ -10,13 +10,8 @@ Debug.setListener(function(){});
 
 var scripts = %DebugGetLoadedScripts();
 scripts.sort(function(a, b) { return a.id - b.id; });
-var user_script_count = 0;
 scripts.reduce(function(prev, cur) {
   assertTrue(prev === undefined || prev.id != cur.id);
-  if (cur.type == 2) user_script_count++;
 });
 
-// Found mjsunit.js and this script.
-assertEquals(2, user_script_count);
-
 Debug.setListener(null);