Remove the unused sizes and encoding properties on Font instances

[Snuffleupagus]

The sizes property doesn't appear to have been used ever since the code was first split into main/worker-threads, which is so many years ago that I wasn't able to easily find exactly in which PR/commit it became unused.

The encoding property is always assigned the properties.baseEncoding value, however the PartialEvaluator doesn't actually compute/set that value any more. Again it was difficult to determine when it became unused, but it's been that way for years.

[Snuffleupagus]

/botio test

[pdfjsbot]

From: Bot.io (Linux m4)

---

Received

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

Live output at: http://54.67.70.0:8877/8b88c55c2a98d5d/output.txt

[pdfjsbot]

From: Bot.io (Windows)

---

Received

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

Live output at: http://54.215.176.217:8877/e156c14842eed0f/output.txt

[pdfjsbot]

From: Bot.io (Windows)

---

Failed

Full output at http://54.215.176.217:8877/e156c14842eed0f/output.txt

Total script time: 1.78 mins

• Font tests: FAILED
• Unit tests: FAILED
• Regression tests: FAILED

Image differences available at: http://54.215.176.217:8877/e156c14842eed0f/reftest-analyzer.html#web=eq.log

[pdfjsbot]

From: Bot.io (Linux m4)

---

Failed

Full output at http://54.67.70.0:8877/8b88c55c2a98d5d/output.txt

Total script time: 19.72 mins

• Font tests: Passed
• Unit tests: Passed
• Regression tests: FAILED

Image differences available at: http://54.67.70.0:8877/8b88c55c2a98d5d/reftest-analyzer.html#web=eq.log

[Snuffleupagus]

I've started looking at

pdf.js/src/core/fonts.js

Lines 1264 to 1265 in fa4b431

	exportData: function Font_exportData() {
	// TODO remove enumerating of the properties, e.g. hardcode exact names.

and have realized that there's unfortunately a large number of apparently unused properties being sent to the main-thread. However, before diving into all of this I wanted to at least remove a few properties that are guaranteed to be unused; hence this PR.

[timvandermeij]

Thank you for cleaning this up!