Fixes insertion of blank pages during print if page sizes differ

[tbtlr]

Fixes https://bugzilla.mozilla.org/show_bug.cgi?id=1020878, https://bugzilla.mozilla.org/show_bug.cgi?id=972677 and probably more.

[yurydelendik]

I wonder if we can just get away with #printContainer and #printContainer > div height:100% attribute.

Not sure what kind of affect setting of the canvas'es style width/height will have on mozPrintCallback polyfill for other browsers. I wish we could set real size of the paper here in inches or mm.

[tbtlr]

We probably can once https://bugzilla.mozilla.org/show_bug.cgi?id=851937 is fixed. On my plate.

[timvandermeij]

I confirm that this fixes the mentioned Bugzilla issues. Furthermore it fixes #4041 too. However, it regresses #6461 (more specifically, this file from that issue: https://www.dropbox.com/s/6lves3ge8s2u48g/bedcard.pdf?dl=0) as it stretches it to match 100% height.

@tobytailor Could you look into what is causing this?

[tbtlr]

@timvandermeij fixed via 708895f.

[timvandermeij]

/botio-linux preview

[pdfjsbot]

From: Bot.io (Linux)

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Received

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

Live output at: http://107.21.233.14:8877/ce4065b613b1c8c/output.txt

[pdfjsbot]

From: Bot.io (Linux)

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Success

Full output at http://107.21.233.14:8877/ce4065b613b1c8c/output.txt

Total script time: 1.01 mins

Published

• Viewer: http://107.21.233.14:8877/ce4065b613b1c8c/web/viewer.html
• B2G Viewer: http://107.21.233.14:8877/ce4065b613b1c8c/extensions/b2g/content/web/viewer.html
• Extension: http://107.21.233.14:8877/ce4065b613b1c8c/extensions/firefox/pdf.js.xpi

[timvandermeij]

Thank you for the patch!

(I have tested this with IE, Edge, Firefox and Chrome and found no regressions for all problematic PDF files from older/current issues, only improvements in terms of no more blank pages and improved scaling.)