Bug 1492014 remove unused Console::GetParentObject() r=baku

WebIDL bindings do not need this method because console is a namespace.
All methods are static.

Depends on D6104

Differential Revision: https://phabricator.services.mozilla.com/D6105

dom/console/Console.h

@@ -48,12 +48,6 @@ public:
   CreateForWorklet(JSContext* aCx, uint64_t aOuterWindowID,
                    uint64_t aInnerWindowID, ErrorResult& aRv);
 
-  // WebIDL methods
-  nsPIDOMWindowInner* GetParentObject() const
-  {
-    return mWindow;
-  }
-
   static void
   Log(const GlobalObject& aGlobal, const Sequence<JS::Value>& aData);