Add more test PDFs to the corpus.

The PDF author gave permission on one bug report, and the other is
self-produced with Chromium.

BUG=chromium:880920,chromium:883026

Change-Id: I1cafa9a777dedfcd8ba61a706d9bedd6a859bfdc
Reviewed-on: https://pdfium-review.googlesource.com/42351
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
diff --git a/pdfium/bug_880920.pdf b/pdfium/bug_880920.pdf
new file mode 100644
index 0000000..d9eb417
--- /dev/null
+++ b/pdfium/bug_880920.pdf
Binary files differ
diff --git a/pdfium/bug_880920_expected.pdf.0.png b/pdfium/bug_880920_expected.pdf.0.png
new file mode 100644
index 0000000..fa2d0c4
--- /dev/null
+++ b/pdfium/bug_880920_expected.pdf.0.png
Binary files differ
diff --git a/pdfium/bug_883026.pdf b/pdfium/bug_883026.pdf
new file mode 100644
index 0000000..04cc5b9
--- /dev/null
+++ b/pdfium/bug_883026.pdf
Binary files differ
diff --git a/pdfium/bug_883026_expected.pdf.0.png b/pdfium/bug_883026_expected.pdf.0.png
new file mode 100644
index 0000000..c86716d
--- /dev/null
+++ b/pdfium/bug_883026_expected.pdf.0.png
Binary files differ