Roll PDFium from 11cb4f444271 to 1877f680e3b2 (4 revisions)

https://pdfium.googlesource.com/pdfium.git/+log/11cb4f444271..1877f680e3b2

2020-09-03 tsepez@chromium.org Make CFX_Font retain its own files.
2020-09-03 tsepez@chromium.org Remove CFGAS_FontMgr::RemoveFont().
2020-09-02 tsepez@chromium.org Check EnumFonts() is fine in XFATestEnvironment::SetUp().
2020-09-02 tsepez@chromium.org Roll v8/ 63911905f..c577d027e (39 commits)

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: Iab288c04df469b449969950b77283c56738192d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2391049Reviewed-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@{#804090}

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': '11cb4f44427147202ecb19919411e599df5a3b2d',
+  'pdfium_revision': '1877f680e3b229bf5b3807f86208921d10128a13',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling BoringSSL
   # and whatever else without interference from each other.