Re-enable a devtools web test

This test was disabled temporarily to land a devtools-frontend change.
This new CL updates the test so it passes with the frontend change and
re-enables it.

Frontend change was:
https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2817904/

Bug: 1197542
Change-Id: Ie7d37924c36a519a482e1670e3ea8e6c55aee66d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2826130


Reviewed-by: Alex Rudenko <alexrudenko@chromium.org>
Commit-Queue: Patrick Brosset <patrick.brosset@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#872379}