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.
There's no good reason, as far as I can tell, to use search-and-replace to include the *stringified* `pdf.scripting.js` file in the built `pdf.sandbox.js` file. Instead we could, and even should, utilize the existing `PDFJSDev.eval(...)`-functionality, which is not only simpler but will also be more efficient as well (no need for a regular expression).
The current location feels somewhat strange, and also inconsistent with the existing way that bundling is done.
Finally, add the version/build numbers at the top of the *built* `pdf.sandbox.js` files, since all other built files include that information given that it's often helpful to be able to easily determine the *exact* version.
