bindings: Update idl-dictionary-unittest

Updates idl-dictionary-unittest to test the change http://crrev.com/574083
Because we can't test IDL dictionary types directly in JS,
we use an interface DictionaryTest as a intermediate path.
This CL also updates the behavior of DictionaryTest to be
consistent with InternalDictionary.


Bug: 855968
Change-Id: I0ad4530a0143185bbf859a0e0b5371e5e0aefa26
Reviewed-on: https://chromium-review.googlesource.com/1136331
Commit-Queue: Hitoshi Yoshida <peria@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Kenichi Ishibashi <bashi@chromium.org>
Reviewed-by: Dominic Farolino <domfarolino@gmail.com>
Cr-Commit-Position: refs/heads/master@{#575548}
7 files changed