[Skia] Suppress Skia test result for checkbox_radiobutton.in.

When Skia is enabled, the rendering result of pixel test
checkbox_radiobutton.in is missing a cross inside a radio button.
Suppresses its test result before crbug.com/pdfium/1736 is fixed.

Bug: pdfium:1736
Change-Id: I6547b3550e2690954d2b13a77356597c522c2a55
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/85973
Commit-Queue: Hui Yingst <nigi@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
diff --git a/testing/SUPPRESSIONS b/testing/SUPPRESSIONS
index 36bd4a7..1ed29ab 100644
--- a/testing/SUPPRESSIONS
+++ b/testing/SUPPRESSIONS
@@ -350,6 +350,9 @@
 # TODO(chromium:451366): Remove after associated bug is fixed
 bug_451366.in * * * *
 
+# TODO(pdfium:1736): Remove after associated bug is fixed
+checkbox_radiobutton.in * * * skia
+
 # TODO(chromium:1028991): Remove after associated bug is fixed
 reset_button.in * * * *