Roll src/third_party/pdfium 763d0d38ddae..918e27142db5 (4 commits)

https://pdfium.googlesource.com/pdfium.git/+log/763d0d38ddae..918e27142db5

git log 763d0d38ddae..918e27142db5 --date=short --first-parent --format='%ad %ae %s'
2019-12-10 tsepez@chromium.org Test CJS_Field::getItemAt() cases from JavaScript.
2019-12-10 thestig@chromium.org Roll build/ 42a74754e..bd45ac1a3 (97 commits)
2019-12-10 thestig@chromium.org Roll build/ 3ba4b9cdc..42a74754e (1 commit)
2019-12-10 thestig@chromium.org Remove unused code from FX_Number.

Created with:
  gclient setdep -r src/third_party/pdfium@918e27142db5

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/pdfium-autoroll
Please CC pdfium-deps-rolls@chromium.org on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

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

Bug: None
Tbr: pdfium-deps-rolls@chromium.org
Change-Id: If74ec9b0522f09a8026bd5927d35271216b7ba45
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1959657Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#723478}

DEPS

@@ -192,7 +192,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFium
   # and whatever else without interference from each other.
-  'pdfium_revision': '763d0d38ddae3c3ff08a721e17ea20268378c3cc',
+  'pdfium_revision': '918e27142db5cc9a85b5eec458b891c947ad17b1',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling BoringSSL
   # and whatever else without interference from each other.