DevTools: Add possibility to break on "wheel" event.

BUG=347562
R=pfeldman
NOTRY=true

Review URL: https://codereview.chromium.org/178473018

git-svn-id: svn://svn.chromium.org/blink/trunk@168364 bbb929c8-8fbe-4397-9dbb-9b2b20218538