Timeline: show selected event details in Tracing mode

Also, highlight record on hover.

BUG=

Review URL: https://codereview.chromium.org/213673005

git-svn-id: svn://svn.chromium.org/blink/trunk@170581 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Timeline: fix frame event dividers in Timeline's main view

BUG=358679

Review URL: https://codereview.chromium.org/221093002

git-svn-id: svn://svn.chromium.org/blink/trunk@170582 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Revert removal of carriage returns from newlines.vtt

R=acolwell@chromium.org
BUG=353373

Review URL: https://codereview.chromium.org/220183002

git-svn-id: svn://svn.chromium.org/blink/trunk@170583 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: Migrate General tab settings to extensions

R=aandrey, pfeldman

Review URL: https://codereview.chromium.org/213423010

git-svn-id: svn://svn.chromium.org/blink/trunk@170585 bbb929c8-8fbe-4397-9dbb-9b2b20218538