Revert of DevTools: Expand protocol to allow setting DOM event breakpoints on a given event target. (https://codereview.chromium.org/320933003/)

Reason for revert:
event-listener-breakpoints.html always timing out on Mac 10.6 (dbg):
http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Mac10.6%20(dbg)

Original issue's description:
> DevTools: Expand protocol to allow setting DOM event breakpoints on a given event target.
> 
> This will allow debugger to pause on "load", "error" and etc. event breakpoints only
> when they happen on XHR event targets.
> 
> BUG=381470
> R=yurys, pfeldman@chromium.org
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=175882

TBR=pfeldman@chromium.org,yurys@chromium.org,aandrey@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=381470

Review URL: https://codereview.chromium.org/322893006

git-svn-id: svn://svn.chromium.org/blink/trunk@175909 bbb929c8-8fbe-4397-9dbb-9b2b20218538