pdf.sandbox.js broken in non-TESTING builds

[Snuffleupagus]

Attach (recommended) or Link to PDF file here: 160F-2019.pdf (from the repository).

Configuration:

• Web browser and its version: Not applicable
• Operating system and its version: Not applicable
• PDF.js version: 2.8.3 (but the issue is older, possibly from PR In order to simplify m-c code, move some in pdf.js #12689)
• Is a browser extension: No

Steps to reproduce the problem:

1. Visit https://mozilla.github.io/pdf.js/web/viewer.html
2. Open the web-console, and run PDFViewerApplication.preferences.set("enableScripting", true);
3. Re-load the viewer
4. Open, e.g. with drag-and-drop or the "Open File"-button, the 160F-2019.pdf file.
5. Note how the pdf.sandbox.js file loads successfully, but trying to execute any code in the sandbox fails with:

   Quickjs -- TypeError: not a function                                        quickjs-eval.js:26:248
   

What is the expected behavior? (add screenshot)
The pdf.sandbox.js file both loads and correctly executes the code.

What went wrong? (add screenshot)
Errors in the QuickJS implementation, and scripting doesn't work.

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Note that this can easily be reproduced locally, to aid debugging and manual testing, by simply:

• Running gulp server and then gulp generic
• Visiting http://localhost:8888/build/generic/web/viewer.html?file=/test/pdfs/160F-2019.pdf
• Then following the STR above, starting with step 2

Furthermore, it seems that this is somehow related to the TESTING build-flag, since if you instead run TESTING=true gulp generic everything works as expected. To me, this would suggest that the QuickJS code somehow (accidentally) depends on the value of parameters that's set when TESTING == true in https://github.com/mozilla/pdf.js/blob/master/src/pdf.sandbox.js

/cc @calixteman