Revert of Fix Runtime.executionContextCreated for crafted iframes. (patchset #6 id:100001 of https://codereview.chromium.org/686763002/)

Reason for revert:
Speculatively reverting to fix telemetry_unittests failures.

Original issue's description:
> Fix Runtime.executionContextCreated for crafted iframes.
> 
> BUG=331407
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=184995

TBR=vsevik@chromium.org,yurys@chromium.org,sergeyv@chromium.org,aandrey@chromium.org,eustas@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=331407

Review URL: https://codereview.chromium.org/711853002

git-svn-id: svn://svn.chromium.org/blink/trunk@184999 bbb929c8-8fbe-4397-9dbb-9b2b20218538