Cover special |xfa| propname in CFXJSE_Engine::NormalPropertyGetter()

Specifically, cfxjse_engine.cpp, lines 334-337 in the 2020-03-20
coverage report.

Change-Id: I0d76c4f98aa848ec9a2f4392b18415c80318c764
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/67731
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
diff --git a/testing/resources/javascript/xfa_specific/xfa_node.in b/testing/resources/javascript/xfa_specific/xfa_node.in
index 99f974b..a0e9b25 100644
--- a/testing/resources/javascript/xfa_specific/xfa_node.in
+++ b/testing/resources/javascript/xfa_specific/xfa_node.in
@@ -80,6 +80,9 @@
         expect("my_doc.setAttribute('fake_value', 'fake_attr')", undefined);
         expect("my_doc.getAttribute('fake_attr')", 'fake_value');
 
+        // Test magic "xfa" property bound to all nodes.
+        expect("my_doc.xfa == xfa", true);
+
         // Test "packet" nodes which are unrecognized tags at XDP level.
         expect("goop", undefined);
         var goop = this.resolveNode('#packet');
diff --git a/testing/resources/javascript/xfa_specific/xfa_node_expected.txt b/testing/resources/javascript/xfa_specific/xfa_node_expected.txt
index d006a78..8455004 100644
--- a/testing/resources/javascript/xfa_specific/xfa_node_expected.txt
+++ b/testing/resources/javascript/xfa_specific/xfa_node_expected.txt
@@ -246,6 +246,7 @@
 Alert: PASS: my_doc.getAttribute('ns') = something
 Alert: PASS: my_doc.setAttribute('fake_value', 'fake_attr') = undefined
 Alert: PASS: my_doc.getAttribute('fake_attr') = fake_value
+Alert: PASS: my_doc.xfa == xfa = true
 Alert: PASS: goop = undefined
 Alert: PASS: goop.className = packet
 Alert: PASS: goop.viscosity = undefined