Return ErrorFont in loadFont when the fontRef is undefined

[Snuffleupagus]

This patch enables loading of: http://www.cruiseshipportal.com/fileadmin/Downloads/CostaConcordia_study.pdf; as reported on IRC: http://logs.glob.uno/?c=mozilla%23pdfjs&s=10+Jun+2014&e=10+Jun+2014#c17609.

The following is an overview of the issues with this particular PDF file:

• The first page contains a Type3 font (R34 (dict) [id: 34, gen: 0]).
• In the CharProcs dictionary, for the three character, there is a reference to the font R98 (dict) [id: 98, gen: 0].
  • This particular font isn't available amongst the font resources for the first page.
  • However it does exist in the font resources for the second page.
  • Since the font isn't available, fontRef is undefined which causes an error preventing the first two pages from rendering.
• This should thus explain why all pages render when the file is opened on the second page, since in that case the missing font has already been loaded by the time it's accessed from the first page.

This patch changes loadFont to return ErrorFont when the fontRef is undefined, thus preventing errors like those described above.
Obviously this isn't a complete solution, but it does reduce the severity of the issue considerably. I'm not even sure if solving this completely is actually feasible (and this kind of issue should be rare), given that it would require waiting for all font resources (hence all pages) to load before attempting to load e.g. Type3 fonts.

[Snuffleupagus]

/botio-linux preview

[pdfjsbot]

From: Bot.io (Linux)

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Received

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

Live output at: http://107.21.233.14:8877/baf29c1645fd70e/output.txt

[pdfjsbot]

From: Bot.io (Linux)

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Success

Full output at http://107.21.233.14:8877/baf29c1645fd70e/output.txt

Total script time: 0.73 mins

Published

• Viewer: http://107.21.233.14:8877/baf29c1645fd70e/web/viewer.html
• B2G Viewer: http://107.21.233.14:8877/baf29c1645fd70e/extensions/b2g/content/web/viewer.html
• Extension: http://107.21.233.14:8877/baf29c1645fd70e/extensions/firefox/pdf.js.xpi
• Extension (AMO): http://107.21.233.14:8877/baf29c1645fd70e/extensions/firefox/pdf.js.amo.xpi

[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://107.21.233.14:8877/079ed930438d053/output.txt

[CodingFabian]

wow fantastic analysis! i was unable to get my head around it.

[pdfjsbot]

From: Bot.io (Linux)

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Success

Full output at http://107.21.233.14:8877/079ed930438d053/output.txt

Total script time: 24.53 mins

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

[yurydelendik]

/botio-windows test

[pdfjsbot]

From: Bot.io (Windows)

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Received

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

Live output at: http://107.22.172.223:8877/b0bfa7ec3a97b4d/output.txt

[pdfjsbot]

From: Bot.io (Windows)

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Success

Full output at http://107.22.172.223:8877/b0bfa7ec3a97b4d/output.txt

Total script time: 21.56 mins

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

[yurydelendik]

Thank you for the pull request