Update pdfium/annots/annotation_strikeout_expected.pdf.0.png with actual strikeout annotation.

Also, add a test case for strikeout annotation with opacity.

R=thestig@chromium.org

Review URL: https://codereview.chromium.org/2203733005 .
diff --git a/pdfium/annots/annotation_strikeout_expected.pdf.0.png b/pdfium/annots/annotation_strikeout_expected.pdf.0.png
index 8f40ed9..8f7e981 100644
--- a/pdfium/annots/annotation_strikeout_expected.pdf.0.png
+++ b/pdfium/annots/annotation_strikeout_expected.pdf.0.png
Binary files differ
diff --git a/pdfium/annots/annotation_strikeout_opacity.pdf b/pdfium/annots/annotation_strikeout_opacity.pdf
new file mode 100644
index 0000000..7fc3259
--- /dev/null
+++ b/pdfium/annots/annotation_strikeout_opacity.pdf
Binary files differ
diff --git a/pdfium/annots/annotation_strikeout_opacity_expected.pdf.0.png b/pdfium/annots/annotation_strikeout_opacity_expected.pdf.0.png
new file mode 100644
index 0000000..a369e9d
--- /dev/null
+++ b/pdfium/annots/annotation_strikeout_opacity_expected.pdf.0.png
Binary files differ