Revert "DevTools: [Styles] Hide live pseudo style updates from inspected page behind an opt-in setting"

Live pseudo-class style updates break certain user workflows

This reverts commit 0152c1bedd2a480520c3e81ade107e247bc4dc71.

TBR=vsevik
NOTRY=true

Review URL: https://codereview.chromium.org/104003008

git-svn-id: svn://svn.chromium.org/blink/trunk@164171 bbb929c8-8fbe-4397-9dbb-9b2b20218538