Revert of [DevTools] Add interstitial events to Inspector domain. (patchset #1 of https://codereview.chromium.org/476423003/)

Reason for revert:
Causes JS compiler errors

Original issue's description:
> [DevTools] Add interstitial events to Inspector domain.
> 
> BUG=404631
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=180666

TBR=pfeldman@chromium.org,dgozman@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=404631

Review URL: https://codereview.chromium.org/488413002

git-svn-id: svn://svn.chromium.org/blink/trunk@180699 bbb929c8-8fbe-4397-9dbb-9b2b20218538