DevTools: split out consolePrompt.css, fix matching bracket style

- Splits out prompt styles into consolePrompt.css
- Do not show background/border on matching brackets if the
  CodeMirror container is not focused

Bug: none
Change-Id: I1955e07ca3289a6781097d0c99467c51336403b9
Reviewed-on: https://chromium-review.googlesource.com/1153468
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Erik Luo <luoe@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579136}
6 files changed