Investigate and potentially improve handling of blocked opening of new tab for "Test" feature

When the user presses the "Test" button in order to try out their translation, our code opens a new tab and puts the translated simulation in it. In our last update to Rosetta we added a feature that allows the client code to log a problem in the server log, and I recently took a look and saw several instances of the following message:

phet-server2.int.colorado.edu rosetta[864582]: error: Client error reported: Unable to open new window

In fact, this occurred 15 times during the month of August.

We may want to investigate this and see if we can make it go away or at least provide the user with a helpful message if they run into this.