Devtools: Add a test on KeyEventUnhandled
Devtools: Add a test on KeyEventUnhandled

This test covers some uncovered code modified by crrev.com/c/1550455

Change-Id: I4ba58b8de040b484f628505093a8754d13e6c5a3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1559321
Auto-Submit: Pâris Meuleman <21699994c82706cfaf054a4aebb77bea1e3b2ee1@chromium.org>
Reviewed-by: Sylvain Defresne <075a4f7f645ca1869f9f673a573a0cfb60d14733@chromium.org>
Reviewed-by: Andrey Kosyakov <03b08926e49d80331ab322c2b9e0332109fbfd39@chromium.org>
Commit-Queue: Pâris Meuleman <21699994c82706cfaf054a4aebb77bea1e3b2ee1@chromium.org>
Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#651648}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: c7b23f3bab4c8180fb856791ecb73f4293fd90a9
ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend