fix(page): navigating 11 pages simultaneously should not throw warning (#3560)

NavigatorWatcher subscribes to Connection to get a `Disconnected` event,
causing us to hit the default max of 10 listeners constraint.

Technically we don't leak anything here and can safely bump
the maxListenersCount to Infinity.

However, we conveniently have `CDPSession`, and
can re-dispatch the event on it and keep the safety check in place.

lib/Connection.js

@@ -228,6 +228,7 @@ class CDPSession extends EventEmitter {
       callback.reject(rewriteError(callback.error, `Protocol error (${callback.method}): Target closed.`));
     this._callbacks.clear();
     this._connection = null;
+    this.emit(CDPSession.Events.Disconnected);
   }
 
   /**
@@ -240,6 +241,11 @@ class CDPSession extends EventEmitter {
     return session;
   }
 }
+
+CDPSession.Events = {
+  Disconnected: Symbol('CDPSession.Events.Disconnected'),
+};
+
 helper.tracePublicAPI(CDPSession);
 
 /**