DevTools: RequestHeadersView: make entire section title clickable.

BUG=422001

Review URL: https://codereview.chromium.org/756993002

git-svn-id: svn://svn.chromium.org/blink/trunk@185954 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: remove intermediate components from split view.

BUG=

Review URL: https://codereview.chromium.org/754853002

git-svn-id: svn://svn.chromium.org/blink/trunk@185979 bbb929c8-8fbe-4397-9dbb-9b2b20218538