Port chrome://bluetooth-internals to the new Mojo JS bindings

This change switches chrome://bluetooth-internals to the new Mojo JS
bindings and updates the tests to match. This required updating the test
runner so that MojoInterfaceInterceptor is available to WebUI in the
same way that addInterfaceOverrideForTesting is for the old bindings.

Bug: 699569
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: Ifb020b12e53d24a6f06b5fce9f462b0fd463193c
Reviewed-on: https://chromium-review.googlesource.com/710636
Reviewed-by: Yuzhu Shen <yzshen@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: calamity <calamity@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Reilly Grant <reillyg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#508301}
28 files changed