src/shared/index.js/observeDev
export function observeDev ( key, callback, options ) {
	var c = ( key = '' + key ).search( /[^\w]/ );
	if ( c > -1 ) {
		var message = "The first argument to component.observe(...) must be the name of a top-level property";
		if ( c > 0 ) message += ", i.e. '" + key.slice( 0, c ) + "' rather than '" + key + "'";

		throw new Error( message );
	}

	return observe.call( this, key, callback, options );
}