connect( document ) {

		this._document = document;

		// use Page Visibility API to avoid large time delta values

		if ( document.hidden !== undefined ) {

			this._pageVisibilityHandler = handleVisibilityChange.bind( this );

			document.addEventListener( 'visibilitychange', this._pageVisibilityHandler, false );

		}

	}
Connect the timer to the given document.Calling this method is not mandatory to
use the timer but enables the usage of the Page Visibility API to avoid large time
delta values.

@param {Document} document - The document.