Revert of CSP: Fire 'load' events even when blocking loads via 'frame-src'. (https://codereview.chromium.org/143323012/)

Reason for revert:
Breaks browser_tests Iframes

Original issue's description:
> CSP: Fire 'load' events even when blocking loads via 'frame-src'.
> 
> If we fire a 'load' event, the frame looks just like any other
> cross-origin load that succeeded. If we don't fire a 'load' event,
> timing attacks can gain knowledge about the URL in the frame by blocking
> the URL in a page's CSP, and waiting long enough to be sure that a 'load'
> event _would_ have fired if the load wasn't blocked.
> 
> R=japhet@chromium.org, jochen@chromium.org
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=165587

TBR=japhet@chromium.org,jochen@chromium.org,mkwst@chromium.org
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/137583009

git-svn-id: svn://svn.chromium.org/blink/trunk@165634 bbb929c8-8fbe-4397-9dbb-9b2b20218538