Add test to ensure Net.* remains unimplemented

Also do the same for other "dangerous" objects.

Bug: chromium:853237
Change-Id: I99ba5037f76e91d386f9b13a614b02101b50499a
Reviewed-on: https://pdfium-review.googlesource.com/c/50850
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

testing/resources/javascript/unsupported.in

diff --git a/testing/resources/javascript/unsupported.in b/testing/resources/javascript/unsupported.in
new file mode 100644
index 0000000..4d1ad5e
--- /dev/null
+++ b/testing/resources/javascript/unsupported.in
@@ -0,0 +1,62 @@
+{{header}}
+{{object 1 0}} <<
+  /Type /Catalog
+  /Pages 2 0 R
+  /OpenAction 10 0 R
+>>
+endobj
+{{object 2 0}} <<
+  /Type /Pages
+  /Count 1
+  /Kids [
+    3 0 R
+  ]
+>>
+endobj
+% Page number 0.
+{{object 3 0}} <<
+  /Type /Page
+  /Parent 2 0 R
+  /MediaBox [0 0 612 792]
+>>
+% OpenAction action
+{{object 10 0}} <<
+  /Type /Action
+  /S /JavaScript
+  /JS 11 0 R
+>>
+endobj
+% JS program to exexute
+{{object 11 0}} <<
+  {{streamlen}}
+>>
+stream
+function expectUnsupportedDangerousFeature(what) {
+  try {
+    var result = eval("typeof " + what);
+    if (result == "undefined") {
+      app.alert('PASS: ' + what + ' is not implemented');
+    } else {
+      app.alert('FAIL: ' + what + ' is implemented, probably a bad idea.');
+      app.alert('FAIL: see https://crbug.com/853237');
+    }
+  } catch (e) {
+    app.alert('Unexpected error ' + e.toString());
+  }
+}
+
+try {
+  expectUnsupportedDangerousFeature("ADBC");
+  expectUnsupportedDangerousFeature("Directory");
+  expectUnsupportedDangerousFeature("Net");
+  expectUnsupportedDangerousFeature("dbg");
+  expectUnsupportedDangerousFeature("security");
+} catch (e) {
+  app.alert('Truly unexpected error: ' + e);
+}
+endstream
+endobj
+{{xref}}
+{{trailer}}
+{{startxref}}
+%%EOF

testing/resources/javascript/unsupported_expected.txt

diff --git a/testing/resources/javascript/unsupported_expected.txt b/testing/resources/javascript/unsupported_expected.txt
new file mode 100644
index 0000000..c9cb77b
--- /dev/null
+++ b/testing/resources/javascript/unsupported_expected.txt
@@ -0,0 +1,5 @@
+Alert: PASS: ADBC is not implemented
+Alert: PASS: Directory is not implemented
+Alert: PASS: Net is not implemented
+Alert: PASS: dbg is not implemented
+Alert: PASS: security is not implemented