DevTools: fix console/timeline toolbar overlap

UI.Toolbars give 'flex: none' to their shadow :host. In [1], an extra
element was placed in between the Toolbar and the flex container,
breaking the 'flex: none'.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/1080036

Screenshot: https://imgur.com/a/wyacU7H

Bug: 860476
Change-Id: If12df76e2bf711c93acee8df5d7f0bbb0a5a868d
Reviewed-on: https://chromium-review.googlesource.com/1139049
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Erik Luo <luoe@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575536}
2 files changed