Revert 166437 "Revert 166309 "Implement DOMWrapperWorlds for wor..."

> Revert 166309 "Implement DOMWrapperWorlds for workers"
> 
> > Implement DOMWrapperWorlds for workers
> > 
> > Currently we have DOMWrapperWorlds for a main world and isolated worlds
> > but don't have DOMWrapperWorlds for worker worlds.
> > 
> > This design is inconsistent and causes a couple of mess in V8 binding.
> > For example, we have to be careful that we're in the main thread when
> > calling DOMWrapperWorld::current() (since workers don't have DOMWrapperWorlds).
> > 
> > We should implement DOMWrapperWorld for worker worlds as well, so that
> > we can treat all worlds consistently.
> > 
> > (Note: This change is necessary for inserting assertions to ScopedPersistent
> > to verify that ScopedPersistent doesn't leak between worlds.)
> > 
> > BUG=339800
> > TBR=abarth (for web/)
> > 
> > Review URL: https://codereview.chromium.org/151443002
> 
> TBR=haraken@chromium.org
> 
> Review URL: https://codereview.chromium.org/155373004

TBR=haraken@chromium.org

Review URL: https://codereview.chromium.org/155403002

git-svn-id: svn://svn.chromium.org/blink/trunk@166438 bbb929c8-8fbe-4397-9dbb-9b2b20218538