We should be testing whether [Exposed=(Foo,Bar)] is working fine or not, and whether [SecureContext] and runtime-enabled features are exposed correctly or not.

However, at a glance, we seem not testing such things.  Let's update the test.

FYI,
https://chromium-review.googlesource.com/c/508328/
should need to update the expectations in bindings/tests/results/.