Attach (recommended) or Link to PDF file here: [160F-2019.pdf](https://github.com/mozilla/pdf.js/blob/a3f6882b06b3ae6b2c02d0be4a650460a84c009c/test/pdfs/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 #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.

---

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 


/* Copyright 2020 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import ModuleLoader from "../external/quickjs/quickjs-eval.js";
import { SandboxSupportBase } from "./pdf.sandbox.external.js";
const pdfjsVersion = PDFJSDev.eval("BUNDLE_VERSION");
const pdfjsBuild = PDFJSDev.eval("BUNDLE_BUILD");
const TESTING =
  typeof PDFJSDev === "undefined" || PDFJSDev.test("!PRODUCTION || TESTING");
class SandboxSupport extends SandboxSupportBase {