This seems to happen more often now, but interestingly it only seems to happen on Linux. The last run was in https://github.com/mozilla/pdf.js/pull/13021#issuecomment-786012076. @calixteman Could you take a look at this to see if we can make the tests pass again?

The relevant log output is:

```
Failures:
1) Interaction in js-colors.pdf must changes colors
  Message:
[31m    In firefox: Expected 'rgba(0, 54, 255, 0.13)' to equal 'rgb(255, 0, 0)'.[0m
  Stack:
    Error: In firefox: Expected 'rgba(0, 54, 255, 0.13)' to equal 'rgb(255, 0, 0)'.
        at <Jasmine>
        at Promise.all.pages.map (/home/ubuntu/pdfjs/botio-files-pdfjs/private/e2b7f68c964756b/test/integration/scripting_spec.js:661:16)
        at process._tickCallback (internal/process/next_tick.js:68:7)
  Message:
[31m    In firefox: Expected 'rgb(255, 0, 0)' to equal 'rgb(0, 255, 0)'.[0m
  Stack:
    Error: In firefox: Expected 'rgb(255, 0, 0)' to equal 'rgb(0, 255, 0)'.
        at <Jasmine>
        at Promise.all.pages.map (/home/ubuntu/pdfjs/botio-files-pdfjs/private/e2b7f68c964756b/test/integration/scripting_spec.js:667:16)
        at process._tickCallback (internal/process/next_tick.js:68:7)
  Message:
[31m    In firefox: Expected 'rgb(0, 255, 0)' to equal 'rgb(0, 0, 255)'.[0m
  Stack:
    Error: In firefox: Expected 'rgb(0, 255, 0)' to equal 'rgb(0, 0, 255)'.
        at <Jasmine>
        at Promise.all.pages.map (/home/ubuntu/pdfjs/botio-files-pdfjs/private/e2b7f68c964756b/test/integration/scripting_spec.js:676:16)
        at process._tickCallback (internal/process/next_tick.js:68:7)
  Message:
[31m    In firefox: Expected 'rgb(0, 0, 255)' to equal 'rgb(255, 0, 0)'.[0m
  Stack:
    Error: In firefox: Expected 'rgb(0, 0, 255)' to equal 'rgb(255, 0, 0)'.
        at <Jasmine>
        at Promise.all.pages.map (/home/ubuntu/pdfjs/botio-files-pdfjs/private/e2b7f68c964756b/test/integration/scripting_spec.js:661:16)
        at process._tickCallback (internal/process/next_tick.js:68:7)
  Message:
[31m    In firefox: Expected 'rgb(255, 0, 0)' to equal 'rgb(0, 255, 0)'.[0m
  Stack:
    Error: In firefox: Expected 'rgb(255, 0, 0)' to equal 'rgb(0, 255, 0)'.
        at <Jasmine>
        at Promise.all.pages.map (/home/ubuntu/pdfjs/botio-files-pdfjs/private/e2b7f68c964756b/test/integration/scripting_spec.js:667:16)
        at process._tickCallback (internal/process/next_tick.js:68:7)
  Message:
[31m    In firefox: Expected 'rgb(0, 255, 0)' to equal 'rgb(0, 0, 255)'.[0m
  Stack:
    Error: In firefox: Expected 'rgb(0, 255, 0)' to equal 'rgb(0, 0, 255)'.
        at <Jasmine>
        at Promise.all.pages.map (/home/ubuntu/pdfjs/botio-files-pdfjs/private/e2b7f68c964756b/test/integration/scripting_spec.js:676:16)
        at process._tickCallback (internal/process/next_tick.js:68:7)
  Message:
[31m    In firefox: Expected 'rgb(0, 0, 255)' to equal 'rgb(255, 0, 0)'.[0m
  Stack:
    Error: In firefox: Expected 'rgb(0, 0, 255)' to equal 'rgb(255, 0, 0)'.
        at <Jasmine>
        at Promise.all.pages.map (/home/ubuntu/pdfjs/botio-files-pdfjs/private/e2b7f68c964756b/test/integration/scripting_spec.js:661:16)
        at process._tickCallback (internal/process/next_tick.js:68:7)
  Message:
[31m    In firefox: Expected 'rgb(255, 0, 0)' to equal 'rgb(0, 255, 0)'.[0m
  Stack:
    Error: In firefox: Expected 'rgb(255, 0, 0)' to equal 'rgb(0, 255, 0)'.
        at <Jasmine>
        at Promise.all.pages.map (/home/ubuntu/pdfjs/botio-files-pdfjs/private/e2b7f68c964756b/test/integration/scripting_spec.js:667:16)
        at process._tickCallback (internal/process/next_tick.js:68:7)
  Message:
[31m    In firefox: Expected 'rgb(0, 255, 0)' to equal 'rgb(0, 0, 255)'.[0m
  Stack:
    Error: In firefox: Expected 'rgb(0, 255, 0)' to equal 'rgb(0, 0, 255)'.
        at <Jasmine>
        at Promise.all.pages.map (/home/ubuntu/pdfjs/botio-files-pdfjs/private/e2b7f68c964756b/test/integration/scripting_spec.js:676:16)
        at process._tickCallback (internal/process/next_tick.js:68:7)
  Message:
[31m    In firefox: Expected 'rgb(0, 0, 255)' to equal 'rgb(255, 0, 0)'.[0m
  Stack:
    Error: In firefox: Expected 'rgb(0, 0, 255)' to equal 'rgb(255, 0, 0)'.
        at <Jasmine>
        at Promise.all.pages.map (/home/ubuntu/pdfjs/botio-files-pdfjs/private/e2b7f68c964756b/test/integration/scripting_spec.js:661:16)
        at process._tickCallback (internal/process/next_tick.js:68:7)
  Message:
[31m    In firefox: Expected 'rgb(255, 0, 0)' to equal 'rgb(0, 255, 0)'.[0m
  Stack:
    Error: In firefox: Expected 'rgb(255, 0, 0)' to equal 'rgb(0, 255, 0)'.
        at <Jasmine>
        at Promise.all.pages.map (/home/ubuntu/pdfjs/botio-files-pdfjs/private/e2b7f68c964756b/test/integration/scripting_spec.js:667:16)
        at process._tickCallback (internal/process/next_tick.js:68:7)
  Message:
[31m    In firefox: Expected 'rgb(0, 255, 0)' to equal 'rgb(0, 0, 255)'.[0m
  Stack:
    Error: In firefox: Expected 'rgb(0, 255, 0)' to equal 'rgb(0, 0, 255)'.
        at <Jasmine>
        at Promise.all.pages.map (/home/ubuntu/pdfjs/botio-files-pdfjs/private/e2b7f68c964756b/test/integration/scripting_spec.js:676:16)
        at process._tickCallback (internal/process/next_tick.js:68:7)
```
for (const num of [6, 4, 2, 1]) {
            await page.click(`option[value=Export${num}]`);
            await page.waitForFunction(
              `document.querySelector("#\\\\33 3R").value !== ""`
            );
            const text = await page.$eval("#\\33 3R", el => el.value);
            expect(text)
              .withContext(`In ${browserName}`)
              .toEqual(`Item${num},Export${num}`);
          }
        })
      );
    });
  });
  describe("in js-colors.pdf", () => {
    let pages;
    beforeAll(async () => {
      pages = await loadAndWait("js-colors.pdf", "#\\33 4R");
    });
    it("must changes colors", async () => {
      await Promise.all(
        pages.map(async ([browserName, page]) => {
          for (const [name, ref] of [
            ["Text1", "#\\33 4R"],
            ["Check1", "#\\33 5R"],
            ["Radio1", "#\\33 7R"],
            ["Choice1", "#\\33 8R"],
          ]) {
            await clearInput(page, "#\\33 4R");
            await page.type("#\\33 4R", `${name}`, {