Tweak the WorkerTask class and the hasJSActions getter

[Snuffleupagus]

• Move some WorkerTask class field definitions out of the constructor

  Also, make use of actually private fields in one case.

• Inline the PDFDocument.prototype._parseHasJSActions method

  This code is short and simple enough that it can just be inlined in the hasJSActions getter.

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Smaller diff with https://github.com/mozilla/pdf.js/pull/21841/changes?w=1

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.24%. Comparing base (d1725ab) to head (67c035f).

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #21841      +/-   ##
==========================================
- Coverage   90.24%   90.24%   -0.01%     
==========================================
  Files         264      264              
  Lines       67286    67285       -1     
==========================================
- Hits        60723    60718       -5     
- Misses       6563     6567       +4     

Flag	Coverage Δ
browsertest	66.32% <25.00%> (+<0.01%)	⬆️
fonttest	8.92% <ø> (ø)
integrationtest	69.43% <91.66%> (-0.02%)	⬇️
unittest	58.44% <100.00%> (-0.01%)	⬇️
unittestcli	56.99% <100.00%> (-0.02%)	⬇️

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[Snuffleupagus]

/botio browsertest

[moz-tools-bot]

From: Bot.io (Windows)

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Received

Command cmd_browsertest from @Snuffleupagus received. Current queue size: 0

Live output at: http://54.193.163.58:8877/21e7be26f3c1643/output.txt

[moz-tools-bot]

From: Bot.io (Linux m4)

---

Received

Command cmd_browsertest from @Snuffleupagus received. Current queue size: 0

Live output at: http://54.241.84.105:8877/81146a0f11c2a6c/output.txt

[timvandermeij]

r=me, with passing tests. Thanks!

[moz-tools-bot]

From: Bot.io (Linux m4)

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Success

Full output at http://54.241.84.105:8877/81146a0f11c2a6c/output.txt

Total script time: 19.02 mins

• Regression tests: Passed

[moz-tools-bot]

From: Bot.io (Windows)

---

Success

Full output at http://54.193.163.58:8877/21e7be26f3c1643/output.txt

Total script time: 23.78 mins

• Regression tests: Passed