This simplifies not just this code, but the unit-tests as well, and should be sufficient as far as I can tell.
Note also that currently, in the *built* `pdf.sandbox.js` file, there's even a line reading `testMode = testMode && false;` because of an accidentally flipped pre-processor statement.
Finally, in the `scripting_spec.js` unit-test, defines `sandboxBundleSrc` at the top of the file to make it easier to find and/or change it when necessary.
* quickjs-eval.js has been generated using https://github.com/mozilla/pdf.js.quickjs/
* lazy load of sandbox code
* Rewrite tests to use the sandbox
* Add a task `watch-sandbox` which update bundle pdf.sandbox.js on change in the sandbox code