Move the IDENTITY_MATRIX constant into src/core/core_utils.js (PR 19772 follow-up)

[Snuffleupagus]

After the changes in PR #19772 the IDENTITY_MATRIX constant is now only used on the worker-thread, which leads to Webpack marking the code as unused in the built pdf.mjs file; see https://phabricator.services.mozilla.com/D244533#change-8oITAexCvrlQ

[Snuffleupagus]

/botio test

[moz-tools-bot]

From: Bot.io (Windows)

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Received

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

Live output at: http://54.193.163.58:8877/882d4115cc4f57a/output.txt

[moz-tools-bot]

From: Bot.io (Linux m4)

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Received

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

Live output at: http://54.241.84.105:8877/4029da4d9871ed1/output.txt

[moz-tools-bot]

From: Bot.io (Linux m4)

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Success

Full output at http://54.241.84.105:8877/4029da4d9871ed1/output.txt

Total script time: 30.86 mins

• Unit tests: Passed
• Integration Tests: Passed
• Regression tests: Passed

[moz-tools-bot]

From: Bot.io (Windows)

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Failed

Full output at http://54.193.163.58:8877/882d4115cc4f57a/output.txt

Total script time: 62.56 mins

• Unit tests: Passed
• Integration Tests: FAILED
• Regression tests: Passed

[calixteman]

Would it be possible to lint that ?

[calixteman]

LGTM. Thank you.

[Snuffleupagus]

Would it be possible to lint that ?

Not easily, since linting is run on the source files rather than on the built files.

Perhaps we could also try and lint the built files, however that'd likely be problematical since we have limited (if any) control of the output format and comments are stripped during building so we couldn't just add eslint-disable statements where needed.

There's also https://webpack.js.org/guides/tree-shaking/ which might help, however it seems like that'd require us to always minify the built files and it's not clear if that'd be desirable (since the code would become unreadable in mozilla-central).