Or, more simply, just open http://www.cic.gc.ca/english/pdf/kits/forms/IMM5257E.pdf and look at the console errors. I currently see:

JS Error: TypeError: Cannot read property 'className' of undefined
Line 290: 	if (oNode.className == "field" && oNode.ui.oneOfChild.className == "checkButton" && oNode.parent.className == "exclGroup"){
JS Error: TypeError: Cannot read property 'className' of undefined
Line 349: 		var sUIClassName = oInvalidNode.ui.oneOfChild.className;
JS Error: TypeError: Cannot read property 'className' of undefined
Line 266: 	if (oNode.className == "field" && oNode.ui.oneOfChild.className == "checkButton" && oNode.parent.className == "exclGroup")
[... repeats of these lines]

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/fc5a4ccc9a0c2008dc7f6fa1788e22c2d64d5e2d

commit fc5a4ccc9a0c2008dc7f6fa1788e22c2d64d5e2d
Author: pdfium-chromium-autoroll <pdfium-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Date: Wed Aug 22 16:54:47 2018

Roll src/third_party/pdfium 94822b57c10e..3caad939aead (20 commits)

https://pdfium.googlesource.com/pdfium.git/+log/94822b57c10e..3caad939aead


git log 94822b57c10e..3caad939aead --date=short --no-merges --format='%ad %ae %s'
2018-08-22 thestig@chromium.org Roll tools/clang/ dec27d726..13b165992 (29 commits)
2018-08-22 thestig@chromium.org Roll third_party/depot_tools/ 5484b866d..02d534031 (93 commits; 18 trivial rolls)
2018-08-22 thestig@chromium.org Roll third_party/zlib/ 39b4a6260..dcf1d0f8c (6 commits)
2018-08-22 thestig@chromium.org Roll third_party/binutils/ e146228c2..4110e0919 (2 commits)
2018-08-22 thestig@chromium.org Roll third_party/googletest/src/ ce468a17c..d52663267 (62 commits)
2018-08-21 tsepez@chromium.org Use UnownedPtr in CPDF_VariableText
2018-08-21 tsepez@chromium.org Use UnownedPtr<> to theme provider in cfwl_widgetproperties.h
2018-08-21 tsepez@chromium.org Use UnownedPtr<> in xfa_resolvenode_rs.h
2018-08-21 hnakashima@chromium.org Remove dead code in CBC_CommonBitMatrix.
2018-08-21 tsepez@chromium.org Use UnownedPtr<> in JBIG2_SDDProc.
2018-08-21 tsepez@chromium.org Use UnownedPtr<> in JBig2_GrrdProc.h.
2018-08-21 hnakashima@chromium.org Remove excessive padding above and below PDF417 barcodes.
2018-08-21 tsepez@chromium.org Use UnownedPtr<> in CJBig2_TRDProc.
2018-08-21 tsepez@chromium.org Avoid copying some big vectors in JBIG2_SymbolDict
2018-08-21 thestig@chromium.org Change GetEmbbedObj() to return an Optional<WideString>.
2018-08-21 tsepez@chromium.org Fix lifetime issue in CJBig2_GRDProc::ProgressiveArithDecodeState
2018-08-21 tsepez@chromium.org Allow creation of a MaybeOwned<T> from UnownedPtr<T>.
2018-08-21 hnakashima@chromium.org Optimize rendering of two dimensional barcodes: defer upscale.
2018-08-21 thestig@chromium.org Fix some IWYU issues in xfa/fxfa/.
2018-08-21 hnakashima@chromium.org Fix one-of property JS errors.


Created with:
  gclient setdep -r src/third_party/pdfium@3caad939aead

The AutoRoll server is located here: https://pdfium-roll.skia.org

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.



BUG= chromium:876222 , chromium:872907 , chromium:872899 
TBR=dsinclair@chromium.org

Change-Id: Ia5aa435aa788b862aaf0c474dd646807a687166b
Reviewed-on: https://chromium-review.googlesource.com/1184402
Reviewed-by: pdfium-chromium-autoroll <pdfium-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Commit-Queue: pdfium-chromium-autoroll <pdfium-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#585095}
[modify] https://crrev.com/fc5a4ccc9a0c2008dc7f6fa1788e22c2d64d5e2d/DEPS