Try to skip mapping of missing TrueType and CIDFontType2 glyphs

[Snuffleupagus]

This PR is based on a patch written by @brendandahl.

The first patch fixed most of the issues, and needed only a very minor adjustment to work correctly for fonts with a CIDToGIDMap.
However in some browsers (e.g. the release version of Firefox), the first patch caused a lot of notdef glyphs to appear in a number of the test files.
After quite a bit of debugging, I found that this was usually an issue with the way that the space character was mapped. In the problematic PDF files, space was usually mapped to various (low) control charCodes.

Since the space glyph (obviously) doesn't need any glyph data, and is thus empty, this causes it to be added to missingGlyphs by sanitizeGlyphLocations().
To work around this, I'm proposing that we also look at toUnicode when building the charCodeToGlyphId map. If the charCode exists in toUnicode the glyph is most likely needed, even if it's empty, hence we add it to the charCodeToGlyphId map. This lets adjustMapping(), if necessary, move the charCode to the Private Use Area and thus fixing the issues with notdef being displayed.

I hope that this approach is reasonable (it passes all tests locally)!

Fixes #5202.
Fixes #5584.
Fixes #3652.
Fixes https://bugzilla.mozilla.org/show_bug.cgi?id=1122998.
Fixes #5664.
Fixes #5681.
Fixes #5704.
Fixes https://bugzilla.mozilla.org/show_bug.cgi?id=893730.

[Snuffleupagus]

/botio test

[pdfjsbot]

From: Bot.io (Linux)

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Received

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

Live output at: http://107.21.233.14:8877/911d81633ed99c6/output.txt

[pdfjsbot]

From: Bot.io (Windows)

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Received

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

Live output at: http://107.22.172.223:8877/caafc54b6760116/output.txt

[pdfjsbot]

From: Bot.io (Windows)

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Success

Full output at http://107.22.172.223:8877/caafc54b6760116/output.txt

Total script time: 17.18 mins

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

[pdfjsbot]

From: Bot.io (Linux)

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Failed

Full output at http://107.21.233.14:8877/911d81633ed99c6/output.txt

Total script time: 22.83 mins

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

Image differences available at: http://107.21.233.14:8877/911d81633ed99c6/reftest-analyzer.html#web=eq.log

[Snuffleupagus]

As far as I'm concerned, the test "failures" on Linux seem to be of two kinds:

• Changes that are almost imperceivable to the naked eye.
• Changes that make the text render better.

/botio-linux preview

[pdfjsbot]

From: Bot.io (Linux)

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

Live output at: http://107.21.233.14:8877/1b8403e2d59c565/output.txt

[pdfjsbot]

From: Bot.io (Linux)

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Success

Full output at http://107.21.233.14:8877/1b8403e2d59c565/output.txt

Total script time: 0.78 mins

Published

• Viewer: http://107.21.233.14:8877/1b8403e2d59c565/web/viewer.html
• B2G Viewer: http://107.21.233.14:8877/1b8403e2d59c565/extensions/b2g/content/web/viewer.html
• Extension: http://107.21.233.14:8877/1b8403e2d59c565/extensions/firefox/pdf.js.xpi

[brendandahl]

/botio test

[pdfjsbot]

From: Bot.io (Windows)

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Received

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

Live output at: http://107.22.172.223:8877/5db5a6c21ccd59b/output.txt

[pdfjsbot]

From: Bot.io (Linux)

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Received

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

Live output at: http://107.21.233.14:8877/5030d99b13f6477/output.txt

[pdfjsbot]

From: Bot.io (Windows)

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Success

Full output at http://107.22.172.223:8877/5db5a6c21ccd59b/output.txt

Total script time: 17.13 mins

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

[pdfjsbot]

From: Bot.io (Linux)

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Failed

Full output at http://107.21.233.14:8877/5030d99b13f6477/output.txt

Total script time: 22.78 mins

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

Image differences available at: http://107.21.233.14:8877/5030d99b13f6477/reftest-analyzer.html#web=eq.log

[brendandahl]

/botio makeref

[pdfjsbot]

From: Bot.io (Windows)

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Received

Command cmd_makeref from @brendandahl received. Current queue size: 0

Live output at: http://107.22.172.223:8877/46f4236638338ee/output.txt

[pdfjsbot]

From: Bot.io (Linux)

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Received

Command cmd_makeref from @brendandahl received. Current queue size: 0

Live output at: http://107.21.233.14:8877/8e408b14ac2a1b9/output.txt

[pdfjsbot]

From: Bot.io (Windows)

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Success

Full output at http://107.22.172.223:8877/46f4236638338ee/output.txt

Total script time: 17.17 mins

• Lint: Passed
• Make references: Passed
• Check references: Passed

[pdfjsbot]

From: Bot.io (Linux)

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Success

Full output at http://107.21.233.14:8877/8e408b14ac2a1b9/output.txt

Total script time: 22.59 mins

• Lint: Passed
• Make references: Passed
• Check references: Passed

[brendandahl]

Thanks for picking this up!