Roll PDFium from c6fa19fccc98 to fe980adabf55 (2 revisions)

https://pdfium.googlesource.com/pdfium.git/+log/c6fa19fccc98..fe980adabf55

2020-08-29 thestig@chromium.org Simplify some code in fx_agg_driver.cpp.
2020-08-29 tsepez@chromium.org Make CXFA_ReadyNodeIterator a stack-only type.

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/+doc/master/autoroll/README.md

Bug: None
Tbr: pdfium-deps-rolls@chromium.org
Change-Id: Ia610a30fdcb371e4664a98288837fbc4b6964485
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2383470Reviewed-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@{#802892}

DEPS

@@ -215,7 +215,7 @@ 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': 'c6fa19fccc985d79622faeb9ecc9f0542bb56b5b',
+  'pdfium_revision': 'fe980adabf55db97c9759407d1c59a6a0b389bbc',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling BoringSSL
   # and whatever else without interference from each other.