Add missing property to event_properties.in

Change-Id: I63c2f2c416d3270061fcffd0c9d0a82c10de88d2
Reviewed-on: https://pdfium-review.googlesource.com/c/44411
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
diff --git a/testing/resources/javascript/event_properties.in b/testing/resources/javascript/event_properties.in
index 495c16b..6f563d1 100644
--- a/testing/resources/javascript/event_properties.in
+++ b/testing/resources/javascript/event_properties.in
@@ -156,6 +156,10 @@
       expect("event.value = 'boo'", "boo");
       expect("event.value", "boo");
 
+      expect("event.willCommit", true);
+      expectError("event.willCommit = 'boo'");
+      expect("event.willCommit", true);
+
       app.alert("*** ending test ***");
     } catch (e) {
       app.alert("Truly unexpected error occured: " + e);
diff --git a/testing/resources/javascript/event_properties_expected.txt b/testing/resources/javascript/event_properties_expected.txt
index ca1cbeb..bdcecc2 100644
--- a/testing/resources/javascript/event_properties_expected.txt
+++ b/testing/resources/javascript/event_properties_expected.txt
@@ -46,4 +46,7 @@
 Alert: PASS: event.value = 
 Alert: PASS: event.value = 'boo' = boo
 Alert: PASS: event.value = boo
+Alert: PASS: event.willCommit = true
+Alert: PASS: event.willCommit = 'boo' threw event.willCommit: Operation not supported.
+Alert: PASS: event.willCommit = true
 Alert: *** ending test ***