DevTools: Migrate some elements tests

Bug: 667560
Change-Id: I8817cabc284c61c6cf25684bffaf5038ef37132f
Reviewed-on: https://chromium-review.googlesource.com/767847
Commit-Queue: Joel Einbinder <einbinder@chromium.org>
Reviewed-by: Andrey Lushnikov <lushnikov@chromium.org>
Reviewed-by: Will Chen <chenwilliam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#516580}
32 files changed