DevTools: reapply r158116 (without 1000 chars limitation this time).
i
BUG=158116
TBR=alph

Review URL: https://codereview.chromium.org/192173003

git-svn-id: svn://svn.chromium.org/blink/trunk@168826 bbb929c8-8fbe-4397-9dbb-9b2b20218538