client/lib/analytics/ad-tracking.js
function setupTwitterGlobal() {
	if ( window.twq ) {
		return;
	}

	const twq = ( window.twq = function() {
		twq.exe ? twq.exe.apply( twq, arguments ) : twq.queue.push( arguments );
	} );
	twq.version = '1.1';
	twq.queue = [];
}
function setupTwitterGlobal() {
	if ( window.twq ) {
		return;
	}

	const twq = ( window.twq = function() {
		twq.exe ? twq.exe.apply( twq, arguments ) : twq.queue.push( arguments );
	} );
	twq.version = '1.1';
	twq.queue = [];
}
This sets up the global `twq` function that Twitter expects.
More info here: https://github.com/Automattic/wp-calypso/pull/10235