Revert of DevTools: Decouple OverridesView from InspectorView with "main.show-drawer-view" action (https://chromiumcodereview.appspot.com/372733002/)

Reason for revert:
Landed by CQ in error, as the offline decision was to use a different approach

Original issue's description:
> DevTools: Implement showing drawer views through "main.show-drawer-view" action
> 
> In particular, this patch is required to decouple the OverridesView from InspectorView.
> 
> R=dgozman, vsevik
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=177584

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

Review URL: https://codereview.chromium.org/365333005

git-svn-id: svn://svn.chromium.org/blink/trunk@177587 bbb929c8-8fbe-4397-9dbb-9b2b20218538