Normalize widget bounding boxes when flattening.

BUG=chromium:890322

Change-Id: I11050b84cf440f8d6bb00c661360de4e389dc031
Reviewed-on: https://pdfium-review.googlesource.com/c/43290
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/testing/resources/bug_890322.in b/testing/resources/bug_890322.in
new file mode 100644
index 0000000..ea55ac6
--- /dev/null
+++ b/testing/resources/bug_890322.in
@@ -0,0 +1,56 @@
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